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1.
PLoS Med ; 19(11): e1004037, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2140363

ABSTRACT

BACKGROUND: Individuals with a prior Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection have a moderate to high degree of protection against reinfection, though seemingly less so when the Omicron variant of SARS-CoV-2 started to circulate. The aim of this study was to evaluate the vaccine effectiveness (VE) against SARS-CoV-2 reinfection, Coronavirus Disease 2019 (COVID-19)-related hospitalization, and COVID-19-related death, in individuals with prior SARS-CoV-2 infection, and to assess the effect of time since vaccination during periods with different dominant SARS-CoV-2 variants. METHODS AND FINDINGS: This study used a nationwide cohort design including all individuals with a confirmed SARS-CoV-2 infection, who were alive, and residing in Denmark between 1 January 2020 and 31 January 2022. Using Danish nationwide registries, we obtained information on SARS-CoV-2 infections, COVID-19 vaccination, age, sex, comorbidity, staying at hospital, and country of origin. The study population included were individuals with prior SARS-CoV-2 infection. Estimates of VE against SARS-CoV-2 reinfection with 95% confidence intervals (CIs) were calculated using a Poisson regression model and adjusted for age, sex, country of origin, comorbidity, staying at hospital, calendar time, and test incidence using a Cox regression model. The VE estimates were calculated separately for three periods with different dominant SARS-CoV-2 variants (Alpha (B.1.1.7), Delta (B.1.617.2), or Omicron (B.1.1.529)) and by time since vaccination using unvaccinated as the reference. In total, 148,527 person-years and 44,192 SARS-CoV-2 infections were included for the analysis regarding reinfections. The study population comprised of 209,814 individuals infected before or during the Alpha period, 292,978 before or during the Delta period, and 245,530 before or during the Omicron period. Of these, 40,281 individuals had completed their primary vaccination series during the Alpha period (19.2%), 190,026 during the Delta period (64.9%), and 158,563 during the Omicron period (64.6%). VE against reinfection following any COVID-19 vaccine type administered in Denmark, peaked at 71% (95% CI: -Inf to 100%) at 104 days or more after vaccination during the Alpha period, 94% (95% CI: 92% to 96%) 14 to 43 days after vaccination during the Delta period, and 60% (95% CI: 58% to 62%) 14 to 43 days after vaccination during the Omicron period. Waning immunity following vaccination was observed and was most pronounced during the Omicron period. Due to too few events, it was not possible to estimate VE for hospitalization and death. Study limitations include potentially undetected reinfections, differences in health-seeking behavior, or risk behavior between the compared groups. CONCLUSIONS: This study shows that in previously infected individuals, completing a primary vaccination series was associated with a significant protection against SARS-CoV-2 reinfection compared with no vaccination. Even though vaccination seems to protect to a lesser degree against reinfection with the Omicron variant, these findings are of public health relevance as they show that previously infected individuals still benefit from COVID-19 vaccination in all three variant periods.


Subject(s)
COVID-19 , Viral Vaccines , Humans , SARS-CoV-2 , Reinfection/epidemiology , Reinfection/prevention & control , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines/therapeutic use , Vaccine Efficacy , Denmark/epidemiology
2.
Sci Rep ; 12(1): 20098, 2022 Nov 22.
Article in English | MEDLINE | ID: covidwho-2133574

ABSTRACT

The in-depth understanding of the dynamics of COVID-19 transmission among different age groups is of great interest for governments and health authorities so that strategies can be devised to reduce the pandemic's detrimental effects. We developed the SIRDV-Virulence (Susceptible-Infected-Recovered-Dead-Vaccinated-Virulence) epidemiological model based on a population balance equation to study the effects virus mutants, vaccination strategies, 'Anti/Non Vaxxer' proportions, and reinfection rates to provide methods to mitigate COVID-19 transmission among the United States population. Based on publicly available data, we obtain the key parameters governing the spread of the pandemic. The results show that a large fraction of infected cases comes from the adult and children populations in the presence of a highly infectious COVID-19 mutant. Given the situation at the end of July 2021, the results show that prioritizing children and adult vaccinations over that of seniors can contain the spread of the active cases, thereby preventing the healthcare system from being overwhelmed and minimizing subsequent deaths. The model suggests that the only option to curb the effects of this pandemic is to reduce the population of unvaccinated individuals. A higher fraction of 'Anti/Non-vaxxers' and a higher reinfection rate can both independently lead to the resurgence of the pandemic.


Subject(s)
COVID-19 , Influenza A Virus, H1N1 Subtype , Adult , Child , United States/epidemiology , Humans , Reinfection/epidemiology , COVID-19/epidemiology , COVID-19/prevention & control , Vaccination/methods , Mutation
3.
Nat Med ; 28(11): 2398-2405, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2116490

ABSTRACT

First infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with increased risk of acute and postacute death and sequelae in various organ systems. Whether reinfection adds to risks incurred after first infection is unclear. Here we used the US Department of Veterans Affairs' national healthcare database to build a cohort of individuals with one SARS-CoV-2 infection (n = 443,588), reinfection (two or more infections, n = 40,947) and a noninfected control (n = 5,334,729). We used inverse probability-weighted survival models to estimate risks and 6-month burdens of death, hospitalization and incident sequelae. Compared to no reinfection, reinfection contributed additional risks of death (hazard ratio (HR) = 2.17, 95% confidence intervals (CI) 1.93-2.45), hospitalization (HR = 3.32, 95% CI 3.13-3.51) and sequelae including pulmonary, cardiovascular, hematological, diabetes, gastrointestinal, kidney, mental health, musculoskeletal and neurological disorders. The risks were evident regardless of vaccination status. The risks were most pronounced in the acute phase but persisted in the postacute phase at 6 months. Compared to noninfected controls, cumulative risks and burdens of repeat infection increased according to the number of infections. Limitations included a cohort of mostly white males. The evidence shows that reinfection further increases risks of death, hospitalization and sequelae in multiple organ systems in the acute and postacute phase. Reducing overall burden of death and disease due to SARS-CoV-2 will require strategies for reinfection prevention.


Subject(s)
COVID-19 , SARS-CoV-2 , Male , Humans , COVID-19/complications , COVID-19/epidemiology , Reinfection/epidemiology , Hospitalization , Cohort Studies , Disease Progression
4.
Lancet Child Adolesc Health ; 6(6): 355-357, 2022 06.
Article in English | MEDLINE | ID: covidwho-2096190
5.
N Engl J Med ; 387(19): 1770-1782, 2022 11 10.
Article in English | MEDLINE | ID: covidwho-2087395

ABSTRACT

BACKGROUND: Information regarding the protection conferred by vaccination and previous infection against infection with the B.1.1.529 (omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited. METHODS: We evaluated the protection conferred by mRNA vaccines and previous infection against infection with the omicron variant in two high-risk populations: residents and staff in the California state prison system. We used a retrospective cohort design to analyze the risk of infection during the omicron wave using data collected from December 24, 2021, through April 14, 2022. Weighted Cox models were used to compare the effectiveness (measured as 1 minus the hazard ratio) of vaccination and previous infection across combinations of vaccination history (stratified according to the number of mRNA doses received) and infection history (none or infection before or during the period of B.1.617.2 [delta]-variant predominance). A secondary analysis used a rolling matched-cohort design to evaluate the effectiveness of three vaccine doses as compared with two doses. RESULTS: Among 59,794 residents and 16,572 staff, the estimated effectiveness of previous infection against omicron infection among unvaccinated persons who had been infected before or during the period of delta predominance ranged from 16.3% (95% confidence interval [CI], 8.1 to 23.7) to 48.9% (95% CI, 41.6 to 55.3). Depending on previous infection status, the estimated effectiveness of vaccination (relative to being unvaccinated and without previous documented infection) ranged from 18.6% (95% CI, 7.7 to 28.1) to 83.2% (95% CI, 77.7 to 87.4) with two vaccine doses and from 40.9% (95% CI, 31.9 to 48.7) to 87.9% (95% CI, 76.0 to 93.9) with three vaccine doses. Incremental effectiveness estimates of a third (booster) dose (relative to two doses) ranged from 25.0% (95% CI, 16.6 to 32.5) to 57.9% (95% CI, 48.4 to 65.7) among persons who either had not had previous documented infection or had been infected before the period of delta predominance. CONCLUSIONS: Our findings in two high-risk populations suggest that mRNA vaccination and previous infection were effective against omicron infection, with lower estimates among those infected before the period of delta predominance. Three vaccine doses offered significantly more protection than two doses, including among previously infected persons.


Subject(s)
COVID-19 Vaccines , COVID-19 , Prisons , Vaccination , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Prisons/statistics & numerical data , Retrospective Studies , SARS-CoV-2 , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/therapeutic use , California/epidemiology , Prisoners/statistics & numerical data , Police/statistics & numerical data , Vaccine Efficacy/statistics & numerical data , Reinfection/epidemiology , Reinfection/prevention & control , Immunization, Secondary/statistics & numerical data
6.
Int J Environ Res Public Health ; 19(21)2022 Oct 24.
Article in English | MEDLINE | ID: covidwho-2081959

ABSTRACT

OBJECTIVES: The actual frequency and the risk factors of SARS-CoV-2 reinfection is still a matter of intense scientific discussion. In this case series, we report three elite athletes who underwent COVID-19 reinfection with a short time frame. CASE PRESENTATIONS: As a part of contact tracing, three speed skaters (22-, 24-, and 29-year-old males) were found to be SARS-CoV-2 positive by polymerase chain reaction (PCR) tests. Later on, only one of the athletes experienced mild symptoms, such as fatigue, loss of smell and taste and subfebrility, while the other two athletes were asymptomatic. Following the quarantine period, detailed return-to-play examinations, including laboratory testing, ECG, 24-h Holter monitoring, transthoracic echocardiography and cardiac magnetic resonance imaging, revealed no apparent abnormality; therefore, the athletes restarted training. After a median of 74 days, all three athletes presented with typical symptoms of COVID-19, such as fever, marked fatigue and headache. SARS-CoV-2 PCR tests were performed again, showing recurrent positivity. Repeated return-to-play assessments were initiated, finding no relevant abnormality. Athletes were also tested for SARS-CoV-2 anti-nucleoprotein antibody titers, showing only modest increases following the second infection. CONCLUSIONS: We report a small cluster of elite athletes who underwent a PCR-proven SARS-CoV-2 reinfection. According to these findings, athletes may be considered as a high-risk group in terms of recurrent COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , Male , Humans , Reinfection/epidemiology , COVID-19/diagnosis , COVID-19/epidemiology , Athletes , Fatigue/etiology
7.
JAMA Netw Open ; 5(10): e2236670, 2022 10 03.
Article in English | MEDLINE | ID: covidwho-2074855

ABSTRACT

Importance: The Omicron variant is phylogenetically and antigenically distinct from earlier SARS-CoV-2 variants and the original vaccine strain. Protection conferred by prior SARS-CoV-2 infection against Omicron reinfection, with and without vaccination, requires quantification. Objective: To estimate the protection against Omicron reinfection and hospitalization conferred by prior heterologous non-Omicron SARS-CoV-2 infection and/or up to 3 doses of an ancestral, Wuhan-like messenger RNA (mRNA) vaccine. Design, Setting, and Participants: This test-negative, population-based case-control study was conducted between December 26, 2021, and March 12, 2022, and included community-dwelling individuals aged 12 years or older who were tested for SARS-CoV-2 infection in the province of Quebec, Canada. Exposures: Prior laboratory-confirmed SARS-CoV-2 infection with or without mRNA vaccination. Main Outcomes and Measures: The main outcome was laboratory-confirmed SARS-CoV-2 reinfection and associated hospitalization, presumed to be associated with the Omicron variant according to genomic surveillance. The odds of prior infection with or without vaccination were compared for case participants with Omicron infection and associated hospitalizations vs test-negative control participants. Estimated protection was derived as 1 - the odds ratio, adjusted for age, sex, testing indication, and epidemiologic week. Analyses were stratified by severity and time since last non-Omicron infection or vaccine dose. Results: This study included 696 439 individuals (224 007 case participants and 472 432 control participants); 62.2% and 63.9% were female and 87.4% and 75.5% were aged 18 to 69 years, respectively. Prior non-Omicron SARS-CoV-2 infection was detected for 9505 case participants (4.2%) and 29 712 control participants (6.3%). Among nonvaccinated individuals, prior non-Omicron infection was associated with a 44% reduction (95% CI, 38%-48%) in Omicron reinfection risk, which decreased from 66% (95% CI, 57%-73%) at 3 to 5 months to 35% (95% CI, 21%-47%) at 9 to 11 months postinfection and was below 30% thereafter. The more severe the prior infection, the greater the risk reduction. Estimated protection (95% CI) against Omicron infection was consistently significantly higher among vaccinated individuals with prior infection compared with vaccinated infection-naive individuals, with 65% (63%-67%) vs 20% (16%-24%) for 1 dose, 68% (67%-70%) vs 42% (41%-44%) for 2 doses, and 83% (81%-84%) vs 73% (72%-73%) for 3 doses. For individuals with prior infection, estimated protection (95% CI) against Omicron-associated hospitalization was 81% (66%-89%) and increased to 86% (77%-99%) with 1, 94% (91%-96%) with 2, and 97% (94%-99%) with 3 mRNA vaccine doses, without signs of waning. Conclusions and Relevance: The findings of this study suggest that vaccination with 2 or 3 mRNA vaccine doses among individuals with prior heterologous SARS-CoV-2 infection provided the greatest protection against Omicron-associated hospitalization. In the context of program goals to prevent severe outcomes and preserve health care system capacity, a third mRNA vaccine dose may add limited protection in twice-vaccinated individuals with prior SARS-CoV-2 infection.


Subject(s)
COVID-19 , Viral Vaccines , COVID-19/epidemiology , COVID-19/prevention & control , Case-Control Studies , Female , Humans , Male , Quebec/epidemiology , RNA, Messenger , Reinfection/epidemiology , Reinfection/prevention & control , SARS-CoV-2/genetics , Vaccines, Synthetic , mRNA Vaccines
8.
BMC Neurol ; 22(1): 379, 2022 Oct 08.
Article in English | MEDLINE | ID: covidwho-2064755

ABSTRACT

BACKGROUND: We conducted this study to compare the risk of reinfection between multiple sclerosis (MS) patients and a control group without MS. METHOD: In this retrospective study, data of all SARS-CoV-2 tests (n = 793,301) and almost all MS patients (n = 10,639) in Isfahan province were collected from January 01, 2020 to August 22, 2021. Of the 2196 MS patients and 793,301 persons from the general population who had been tested at least once, 3 control for each MS patient were identified, leaving 1560 MS patients and 4680 controls without MS. We compared the risk of reinfection after 90 days of a primary infection between those with and without a previous positive COVID-19 test. RESULTS: 736 (47.2%) MS patients and 2013 (43.0%) control individuals had at least one positive test. A total of 17 (2.3%) and 22 (1.1%) possible reinfections in MS and control groups were observed. The estimated protection against reinfection in all MS patients, MS patients on rituximab, MS patients on DMTs rather than rituximab, and controls were 68.2% (46.2, 81.2%), 57.4% (- 0.1, 83.1%), 71.5% (45.5, 85.2%), and 82.1% (72.1, 88.5%), respectively. We found no statistically significant difference in estimated protection (p = 0.123) and odd of reinfection (adjusted OR: 2.01 [0.98, 4.08]) between all MS patients and control group. Two patients were hospitalized at first infection but none required hospitalization at reinfection event. CONCLUSIONS: MS patients on rituximab may be at a greater risk of reinfection. Further studies are required to assess the risk of the second reinfection among the MS population.


Subject(s)
COVID-19 , Multiple Sclerosis , COVID-19/epidemiology , Humans , Multiple Sclerosis/epidemiology , Reinfection/epidemiology , Retrospective Studies , Rituximab , SARS-CoV-2
9.
Clin Drug Investig ; 42(10): 807-812, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-2027720

ABSTRACT

BACKGROUND: The enduring presence of COVID-19 and subsequent increasing incidence of COVID-19 reinfection has prompted evaluation of associated risk factors, particularly the role of immunosuppression. OBJECTIVE: The objective of this study was to characterize cases indicative of COVID-19 reinfection with respect to their reported use of immunosuppressant/immunomodulating agents. METHODS: This cross-sectional observational study leveraged the Pfizer global safety database (SDB) containing adverse event data collected in association with use of Pfizer products between 1 October 2019, and 30 June 2022. Selected Medical Dictionary for Drug Regulatory Activities (MedDRA®) Preferred Terms were used to identify COVID-19 cases; the search was further refined to comprise cases that subsequently reported events potentially indicative of COVID-19 reinfection. RESULTS: Of the cumulative total of 218,242 COVID-19 cases reported into the SDB, 4590 cases (2.1%) involving potential COVID-19 reinfection were identified. Of these 4590 cases of potential Covid-19 reinfection, a total of 134 cases reported COVID-19 specifically during treatment with pharmaceutical products, of which approximately 16% (21/134) of cases reported use of immunosuppressant/immunomodulating agents. Likewise, in the overall dataset (213,652 cases; excluding the 4590 cases involving potential COVID-19 recurrence), the percentage of reported immunosuppressant/immunomodulating agents was low (12%). In applying similar parameters to a dataset that excludes COVID-19 vaccine cases, 18% of cases reported use of immunosuppressant/immunomodulating agents (similar to the aforementioned 16% of cases reported from the overall total dataset that was inclusive of vaccine cases). CONCLUSION: This pharmacovigilance study provides a characterization of cases indicative of COVID-19 reinfection with respect to reported use of immunosuppressant/immunomodulating agents. The observations generated from this cross-sectional observational analysis may prompt further research into the role of immunosuppression in COVID-19 reinfection, in an effort to better inform clinical practice and patient management.


Subject(s)
COVID-19 , Drug-Related Side Effects and Adverse Reactions , Immunomodulating Agents , Immunosuppressive Agents , Adverse Drug Reaction Reporting Systems , COVID-19/epidemiology , COVID-19 Vaccines/administration & dosage , Cross-Sectional Studies , Humans , Immunomodulating Agents/adverse effects , Immunosuppressive Agents/adverse effects , Pharmaceutical Preparations , Reinfection/epidemiology
10.
West Afr J Med ; 39(8): 777-780, 2022 Aug 31.
Article in English | MEDLINE | ID: covidwho-2012197

ABSTRACT

BACKGROUND: Reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has important public health implications pertaining to herd immunity and durability of protection from vaccines. A small but growing number of cases have been reported globally but none from Africa. This is due, in part, to adherence to definitions based on genetic sequencing, the capabilities of which are in short supply on the continent. METHODS: Based on epidemiological and clinical parameters, we report the first two cases of SARS-CoV-2 reinfection from a Nigerian tertiary hospital managing coronavirus disease 2019 (COVID-19) patients. RESULT: Two cases of SARS-CoV-2 reinfection were seen in December, 2020 and January, 2021. Both were males associated with a healthcare setting and aged 37 and 38 years respectively. The number of days between the first infection and the second ranged from 160-196 days. Symptoms ranged from mild to moderate and they recovered without sequelae. CONCLUSION: Public health action, including risk communication and reinfection surveillance backed by genomic sequencing, is advocated.


CONTEXTE: La réinfection par le coronavirus 2 du syndrome respiratoire aigu sévère (SRAS-CoV-2) a des implications importantes pour la santé publique en ce qui concerne l'immunité du troupeau et la durabilité de la protection contre les vaccins. Un nombre petit mais croissant de cas a été signalé dans le monde, mais aucun en Afrique. Cela est dû, en partie, au respect des définitions basées sur le séquençage génétique, dont les capacités sont rares sur le continent. MÉTHODES: Sur la base de paramètres épidémiologiques et cliniques, nous rapportons les deux premiers cas de réinfection par le SRAS-CoV-2 d'un hôpital tertiaire nigérian prenant en charge des patients atteints de la maladie à coronavirus 2019 (COVID-19). RÉSULTAT: Deux cas de réinfection par le SRAS-CoV-2 ont été observés en décembre 2020 et janvier 2021. Tous deux étaient des hommes associés à un établissement de soins de santé et âgés respectivement de 37 et 38 ans. Le nombre de jours entre la première infection et la seconde variait de 160 à 196 jours. Les symptômes variaient de légers à modérés et ils se sont rétablis sans séquelles. CONCLUSION: Une action de santé publique, y compris la communication des risques et la surveillance des réinfections appuyées par le séquençage génomique, est préconisée. MOTS CLÉS: COVID-19; SRAS-CoV-2; Réinfection; Nigeria; Pandémie.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , Female , Humans , Male , Nigeria/epidemiology , Reinfection/epidemiology , SARS-CoV-2
11.
Ann Intern Med ; 175(5): 674-681, 2022 05.
Article in English | MEDLINE | ID: covidwho-1975317

ABSTRACT

BACKGROUND: There is insufficient evidence regarding the magnitude and durability of protection conferred by a combined effect of naturally acquired immunity after SARS-CoV-2 infection and vaccine-induced immunity. OBJECTIVE: To compare the incidence rate of SARS-CoV-2 reinfection in previously infected persons to that of previously infected persons who subsequently received a single dose of BNT162b2 messenger RNA vaccine. DESIGN: A retrospective cohort study emulating a randomized controlled target trial through a series of nested trials. SETTING: Nationally centralized database of Maccabi Healthcare Services, Israel. PARTICIPANTS: Persons with documented SARS-CoV-2 infection who did not receive subsequent SARS-CoV-2 vaccination were compared with persons with documented SARS-CoV-2 infection who received a single dose of the BNT162b2 vaccine at least 3 months after infection. INTERVENTION: Forty-one randomized controlled trials were emulated, in which 107 413 Maccabi Healthcare Services' members aged 16 years and older were eligible for at least 1 trial. MEASUREMENTS: SARS-CoV-2-related outcomes of infection, symptomatic disease, hospitalization, and death, between 2 March and 13 December 2021. RESULTS: A statistically significant decreased risk (hazard ratio, 0.18 [95% CI, 0.15 to 0.20]) for reinfection was found among persons who were previously infected and then vaccinated versus those who were previously infected but remained unvaccinated. In addition, there was a decreased risk for symptomatic disease (hazard ratio, 0.24 [CI, 0.20 to 0.29]) among previously infected and vaccinated persons compared with those who were not vaccinated after infection. No COVID-19-related mortality cases were found. LIMITATION: Hybrid protection against non-Delta variants could not be inferred. CONCLUSION: Persons previously infected with SARS-CoV-2 gained additional protection against reinfection and COVID-19 from a subsequent single dose of the BNT162b2 vaccine. Nonetheless, even without a subsequent vaccination, reinfection appeared relatively rare. PRIMARY FUNDING SOURCE: None.


Subject(s)
COVID-19 , Vaccines , Adaptive Immunity , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Humans , Incidence , Reinfection/epidemiology , Reinfection/prevention & control , Retrospective Studies , SARS-CoV-2 , Vaccines, Synthetic
12.
BMC Infect Dis ; 22(1): 592, 2022 Jul 04.
Article in English | MEDLINE | ID: covidwho-1974119

ABSTRACT

BACKGROUND: SARS-CoV-2 reinfections are a public health concern because of the potential for transmission and clinical disease, and because of our limited understanding of whether and how well an infection confers protection against subsequent infections. Despite the public health importance, few studies have reported rigorous estimates of reinfection risk. METHODS: Leveraging Indiana University's comprehensive testing program to identify both asymptomatic and symptomatic SARS-CoV-2 cases, we estimated the incidence of SARS-CoV-2 reinfection among students, faculty, and staff across the 2020-2021 academic year. We contextualized the reinfection data with information on key covariates: age, sex, Greek organization membership, student vs faculty/staff affiliation, and testing type. RESULTS: Among 12,272 people with primary infections, we found a low level of SARS-CoV-2 reinfections (0.6%; 0.4 per 10,000 person-days). We observed higher risk for SARS-CoV-2 reinfections in Greek-affiliated students. CONCLUSIONS: We found evidence for low levels of SARS-CoV-2 reinfection in a large multi-campus university population during a time-period prior to widespread COVID-19 vaccination.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , COVID-19 Vaccines , Humans , Reinfection/epidemiology , SARS-CoV-2 , Universities
14.
Eur J Clin Invest ; 52(10): e13845, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-1968090

ABSTRACT

INTRODUCTION: A precise estimate of the frequency and severity of SARS-CoV-2 reinfections would be critical to optimize restriction and vaccination policies for the hundreds of millions previously infected subjects. We performed a meta-analysis to evaluate the risk of reinfection and COVID-19 following primary infection. METHODS: We searched MedLine, Scopus and preprint repositories for cohort studies evaluating the onset of new infections among baseline SARS-CoV-2-positive subjects. Random-effect meta-analyses of proportions were stratified by gender, exposure risk, vaccination status, viral strain, time between episodes, and reinfection definition. RESULTS: Ninety-one studies, enrolling 15,034,624 subjects, were included. Overall, 158,478 reinfections were recorded, corresponding to a pooled rate of 0.97% (95% CI: 0.71%-1.27%), with no substantial differences by definition criteria, exposure risk or gender. Reinfection rates were still 0.66% after ≥12 months from first infection, and the risk was substantially lower among vaccinated subjects (0.32% vs. 0.74% for unvaccinated individuals). During the first 3 months of Omicron wave, the reinfection rates reached 3.31%. Overall rates of severe/lethal COVID-19 were very low (2-7 per 10,000 subjects according to definition criteria) and were not affected by strain predominance. CONCLUSIONS: A strong natural immunity follows the primary infection and may last for more than one year, suggesting that the risk and health care needs of recovered subjects might be limited. Although the reinfection rates considerably increased during the Omicron wave, the risk of a secondary severe or lethal disease remained very low. The risk-benefit profile of multiple vaccine doses for this subset of population needs to be carefully evaluated.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , Humans , Immunity, Innate , Reinfection/epidemiology , SARS-CoV-2 , Vaccination
15.
J Infect Public Health ; 15(9): 966-969, 2022 Sep.
Article in English | MEDLINE | ID: covidwho-1966858

ABSTRACT

We report a cluster of 12 cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection in a long-term care facility in South Korea. There were two outbreaks of SARS-CoV-2 infection in the facility at the beginning and end of October 2021, respectively. All residents in the facility were screened for SARS-CoV-2 infection using RT-PCR as part of the investigation of the second outbreak. Twelve residents, who had infection confirmed during the first outbreak, were found to be re-positive for RT-PCR test at the second outbreak. 8 Of 12 RT-PCR re-positive cases were confirmed as reinfections based on investigation through the whole genome sequencing, viral culture, and serological analysis, despite of the short interval between the first and second outbreaks (29-33 days) and a history of full vaccination for 7 of the 12 re-positive cases. This study suggests that decreased immunity and underlying health condition in older adults makes them susceptible to reinfection, highlighting the importance of prevention and control measures regardless of vaccination status in long-term care settings.


Subject(s)
COVID-19 , SARS-CoV-2 , Aged , COVID-19/epidemiology , Disease Outbreaks/prevention & control , Humans , Long-Term Care , Nursing Homes , Reinfection/epidemiology
16.
Int J Infect Dis ; 123: 9-16, 2022 Oct.
Article in English | MEDLINE | ID: covidwho-1966628

ABSTRACT

OBJECTIVES: SARS-CoV-2 vaccination has been shown to reduce infection severity; however, the reinfection frequency among unvaccinated, partially vaccinated, and fully vaccinated individuals remains unclear. This study aims to elucidate the rates of and factors associated with such occurrences. METHODS: This retrospective epidemiological report included 1362 COVID-19 reinfection cases in Bahrain between April 2020 and July 2021. We analyzed differences in disease severity and reinfection characteristics among various vaccination statuses: fully vaccinated, interrupted vaccination, one-dose vaccination, postreinfection vaccination, and unvaccinated. RESULTS: Reinfection cases increased from zero per month in April-June 2020 to a sharp peak of 579 in May 2021. A significantly larger proportion of reinfected individuals were male (60.3%, P <0.0001). Reinfection episodes were highest among those 30-39 years of age (29.7%). The fewest reinfection episodes occurred at 3-6 months after the first infection (20.6%) and most occurred ≥9 months after the initial infection (46.4%). Most individuals were asymptomatic during both episodes (35.7%). Reinfection disease severity was mild, with vaccinated patients less likely to have symptomatic reinfection (odds ratio 0.71, P = 0.004). Only 6.6% of reinfected patients required hospitalization. One death was recorded; the patient belonged to the unvaccinated group. CONCLUSION: Vaccine-induced immunity and previous infection with or without vaccination were effective in reducing reinfection disease severity.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Female , Humans , Male , Reinfection/epidemiology , Retrospective Studies
17.
JAMA Netw Open ; 5(7): e2223917, 2022 07 01.
Article in English | MEDLINE | ID: covidwho-1958651

ABSTRACT

Importance: The benefit of vaccination for preventing reinfection among individuals who have been previously infected with SARS-CoV-2 is largely unknown. Objective: To obtain population-based estimates of the probability of SARS-CoV-2 reinfection and the effectiveness associated with vaccination after recovery from COVID-19. Design, Setting, and Participants: This cohort study used Rhode Island statewide surveillance data from March 1, 2020, to December 9, 2021, on COVID-19 vaccinations, laboratory-confirmed cases, hospitalizations, and fatalities to conduct a population-based, retrospective study during periods when wild type, Alpha, and Delta strains of SARS-CoV-2 were predominant. Participants included Rhode Island residents aged 12 years and older who were previously diagnosed with COVID-19 and unvaccinated at the time of first infection, stratified into 3 subpopulations: long-term congregate care (LTCC) residents, LTCC employees, and the general population (ie, individuals not associated with congregate settings). Data were analyzed from October 2021 to January 2022. Exposures: Completion of the primary vaccination series, defined as 14 days after the second dose of an mRNA vaccine or 1 dose of vector virus vaccine. Main Outcomes and Measures: The main outcome was SARS-CoV-2 reinfection, defined as a laboratory-confirmed positive result on a polymerase chain reaction (PCR) or antigen test at least 90 days after the first laboratory-confirmed positive result on a PCR or antigen test. Results: Overall, 3124 LTCC residents (median [IQR] age, 81 [71-89]; 1675 [53.6%] females), 2877 LTCC employees (median [IQR] age, 41 [30-53]; 2186 [76.0%] females), and 94 516 members of the general population (median [IQR] age, 35 [24-52] years; 45 030 [47.6%] females) met eligibility criteria. Probability of reinfection at 9 months for those who remained unvaccinated after recovery from prior COVID-19 was 13.0% (95% CI, 12.0%-14.0%) among LTCC residents, 10.0% (95% CI, 8.8%-11.5%) among LTCC employees, and 1.9% (95% CI, 1.8%-2.0%) among the general population. Completion of the primary vaccination series after infection was associated with 49% (95% CI, 27%-65%) protection among LTCC residents, 47% (95% CI, 19%-65%) protection among LTCC employees, and 62% (95% CI, 56%-68%) protection in the general population against reinfection, adjusting for potential sociodemographic and clinical confounders and temporal variation in infection rates. Conclusions and Relevance: These findings suggest that risk of SARS-CoV-2 reinfection after recovery from COVID-19 was relatively high among individuals who remained unvaccinated. Vaccination after recovery from COVID-19 was associated with reducing risk of reinfection by approximately half.


Subject(s)
COVID-19 , Reinfection , Adult , Aged, 80 and over , COVID-19/epidemiology , COVID-19/prevention & control , Cohort Studies , Female , Humans , Male , Reinfection/epidemiology , Reinfection/prevention & control , Retrospective Studies , SARS-CoV-2 , Vaccination , Vaccines, Synthetic , mRNA Vaccines
18.
J Med Virol ; 94(11): 5589-5592, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-1955921

ABSTRACT

To better understand the epidemiology of SARS-CoV-2 reinfections, we analyzed national data from South Korean who were followed longitudinally from January 2020 to April 2022. We conducted a nationwide retrospective cohort study to estimate possible SARS-CoV-2 reinfection rates in all residents in South Korea, with at least two episodes of laboratory-confirmed SARS-CoV-2 infection by reverse-transcriptase polymerase chain reaction or rapid antigen test (RAT) performed at least 45 or more days between both episodes, between January 2020 and April 2022. There were 16 130 855 laboratory-confirmed SARS-CoV-2 cases in South Korea, with 55 841 (346.2 per 100 000; or 0.3% of all infections) cases of possible reinfections. The reinfection rate has increased from 6.0 cases per 100 000 during Pre-Delta period to 128.0 cases per 100 000 and 355.1 cases per 100 000 during Delta and Omicron periods, respectively. Persons with one dose of vaccination had the highest reinfection rate of 642.2 per 100 000, followed by unvaccinated persons (536.2/100 000) and two-dose vaccinated persons (406.3/100 000). Our finding suggests that the majority of possible reinfections occurred following the emergence of new variants.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , Humans , Reinfection/epidemiology , Retrospective Studies , SARS-CoV-2 , Vaccination
19.
Int J Infect Dis ; 122: 758-766, 2022 Sep.
Article in English | MEDLINE | ID: covidwho-1936534

ABSTRACT

BACKGROUND: The characterization of reinfection with SARS-CoV-2 has been a subject of concern and controversy, especially with the surge of infections with highly transmissible variants worldwide. METHODS: This retrospective national study used comorbidities, vaccination status, SARS-CoV-2 variants of concern, and demographics data to profile participants who were reinfected with SARS-CoV-2, defined as having two reverse transcriptase-polymerase chain reaction-positive SARS-CoV-2 tests within at least 90 days apart. A multivariate logistic regression model assessed the risk factors associated with reinfection . Two control groups were selected: nonreinfected participants reporting a positive test (control group one) and those reporting a negative test (control group two). RESULTS: Between March 2020 and December 2021, 4454 reinfected participants were identified in Saudi Arabia (0.8%, 95% confidence interval [CI] 0.7-0.8). The majority (67.3%) were unvaccinated (95% CI 65.9-68.7) and 0.8% (95% CI 0.6-1.1) had severe or fatal SARS-CoV-2 disease. COVID-19 vaccines were 100% effective against mortality in reinfected individuals who received at least one dose, whereas it conferred 61% (odds ratio [OR] 0.4, 95% CI 0.1-1.0) additional protection against severe disease after the first dose and 100% after the second dose. In the risk factor analysis, reinfection was highly associated with comorbidities, such as HIV (OR 2.5, 95% CI 1.3-5.2; P = 0.009), obesity (OR 2.3, 95% CI 1.3-3.9; P = 0.003), pregnancy (OR 3.2, 95% CI 1.4-7.4; P = 0.005), and working in health care facilities (OR 6.1, 95% CI 3.1-12.9; P <0.0001). The delta variant (B.1.617.2) was the most frequent variant of concern among the reinfected cohort. CONCLUSION: This in-depth study of the reinfection profile identified risk factors and highlighted the associated SARS-CoV-2 variants. Results showed that naturally acquired immunity to SARS-CoV-2 through multiple reinfections together with vaccine-induced immunity provided substantial protection against severe SARS-CoV-2 disease and mortality.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , COVID-19 Vaccines , Humans , Reinfection/epidemiology , Retrospective Studies , SARS-CoV-2 , Saudi Arabia/epidemiology
20.
Glob Health Res Policy ; 7(1): 12, 2022 04 29.
Article in English | MEDLINE | ID: covidwho-1933159

ABSTRACT

BACKGROUND: With the continuation of the COVID-19 pandemic, some COVID-19 patients have become reinfected with the virus. Viral gene sequencing has found that some of these patients were reinfected by the different and others by same strains. This has raised concerns about the effectiveness of immunity after infection and the reliability of vaccines. To this end, we conducted a systematic review to assess the characteristics of patients with reinfection and possible causes. METHODS: A systematic search was conducted across eight databases: PubMed, Embase, Web of Science, The Cochrane Library, CNKI, WanFang, VIP and SinoMed from December 1, 2019 to September 1, 2021. The quality of included studies were assessed using JBI critical appraisal tools and Newcastle-Ottawa Scale. RESULTS: This study included 50 studies from 20 countries. There were 118 cases of reinfection. Twenty-five patients were reported to have at least one complication. The shortest duration between the first infection and reinfection was 19 days and the longest was 293 days. During the first infection and reinfection, cough (51.6% and 43.9%) and fever (50% and 30.3%) were the most common symptoms respectively. Nine patients recovered, seven patients died, and five patients were hospitalized, but 97 patients' prognosis were unknown. B.1 is the most common variant strain at the first infection. B.1.1.7, B.1.128 and B.1.351 were the most common variant strains at reinfection. Thirty-three patients were infected by different strains and 9 patients were reported as being infected with the same strain. CONCLUSIONS: Our research shows that it is possible for rehabilitated patients to be reinfected by SARS-COV-2. To date, the causes and risk factors of COVID-19 reinfection are not fully understood. For patients with reinfection, the diagnosis and management should be consistent with the treatment of the first infection. The public, including rehabilitated patients, should be fully vaccinated, wear masks in public places, and pay attention to maintaining social distance to avoid reinfection with the virus.


Subject(s)
COVID-19 , Reinfection , COVID-19/epidemiology , Humans , Pandemics , Reinfection/epidemiology , Reproducibility of Results , SARS-CoV-2
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