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1.
MMWR Morb Mortal Wkly Rep ; 71(17): 592-596, 2022 Apr 29.
Article in English | MEDLINE | ID: covidwho-2204198

ABSTRACT

On August 29, 2021, the United States government oversaw the emergent establishment of Operation Allies Welcome (OAW), led by the U.S. Department of Homeland Security (DHS) and implemented by the U.S. Department of Defense (DoD) and U.S. Department of State (DoS), to safely resettle U.S. citizens and Afghan nationals from Afghanistan to the United States. Evacuees were temporarily housed at several overseas locations in Europe and Asia* before being transported via military and charter flights through two U.S. international airports, and onward to eight U.S. military bases,† with hotel A used for isolation and quarantine of persons with or exposed to certain infectious diseases.§ On August 30, CDC issued an Epi-X notice encouraging public health officials to maintain vigilance for measles among Afghan evacuees because of an ongoing measles outbreak in Afghanistan (25,988 clinical cases reported nationwide during January-November 2021) (1) and low routine measles vaccination coverage (66% and 43% for the first and second doses, respectively, in 2020) (2).


Subject(s)
Communicable Diseases , Measles , Communicable Diseases/epidemiology , Disease Outbreaks/prevention & control , Humans , Measles/epidemiology , Measles/prevention & control , Public Health , United States/epidemiology , Vaccination
2.
Epidemiology ; 33(6): 797-807, 2022 Nov 01.
Article in English | MEDLINE | ID: covidwho-2190880

ABSTRACT

BACKGROUND: Marine recruits training at Parris Island experienced an unexpectedly high rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, despite preventive measures including a supervised, 2-week, pre-entry quarantine. We characterize SARS-CoV-2 transmission in this cohort. METHODS: Between May and November 2020, we monitored 2,469 unvaccinated, mostly male, Marine recruits prospectively during basic training. If participants tested negative for SARS-CoV-2 by quantitative polymerase chain reaction (qPCR) at the end of quarantine, they were transferred to the training site in segregated companies and underwent biweekly testing for 6 weeks. We assessed the effects of coronavirus disease 2019 (COVID-19) prevention measures on other respiratory infections with passive surveillance data, performed phylogenetic analysis, and modeled transmission dynamics and testing regimens. RESULTS: Preventive measures were associated with drastically lower rates of other respiratory illnesses. However, among the trainees, 1,107 (44.8%) tested SARS-CoV-2-positive, with either mild or no symptoms. Phylogenetic analysis of viral genomes from 580 participants revealed that all cases but one were linked to five independent introductions, each characterized by accumulation of mutations across and within companies, and similar viral isolates in individuals from the same company. Variation in company transmission rates (mean reproduction number R 0 ; 5.5 [95% confidence interval [CI], 5.0, 6.1]) could be accounted for by multiple initial cases within a company and superspreader events. Simulations indicate that frequent rapid-report testing with case isolation may minimize outbreaks. CONCLUSIONS: Transmission of wild-type SARS-CoV-2 among Marine recruits was approximately twice that seen in the community. Insights from SARS-CoV-2 outbreak dynamics and mutations spread in a remote, congregate setting may inform effective mitigation strategies.


Subject(s)
COVID-19 , Disease Outbreaks , Military Personnel , COVID-19/epidemiology , COVID-19/prevention & control , Disease Outbreaks/prevention & control , Female , Humans , Male , Military Personnel/statistics & numerical data , Phylogeny , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , United States/epidemiology
4.
JMIR Public Health Surveill ; 7(10): e26840, 2021 10 07.
Article in English | MEDLINE | ID: covidwho-2141319

ABSTRACT

BACKGROUND: The outbreak of COVID-19 in China occurred around the Chinese New Year (January 25, 2020), and infections decreased continuously afterward. General adoption of preventive measures during the Chinese New Year period was crucial in driving the decline. It is imperative to investigate preventive behaviors among Chinese university students, who could have spread COVID-19 when travelling home during the Chinese New Year break. OBJECTIVE: In this study, we investigated levels of COVID-19-related personal measures undertaken during the 7-day Chinese New Year holidays by university students in China, and associated COVID-19-related cognitive factors. METHODS: A cross-sectional anonymous web-based survey was conducted during the period from February 1 to 10, 2020. Data from 23,863 students (from 26 universities, 16 cities, 13 provincial-level regions) about personal measures (frequent face-mask wearing, frequent handwashing, frequent home staying, and an indicator that combined the 3 behaviors) were analyzed (overall response rate 70%). Multilevel multiple logistic regression analysis was performed. RESULTS: Only 28.0% of respondents (6684/23,863) had left home for >4 hours, and 49.3% (11,757/23,863) had never left home during the 7-day Chinese New Year period; 79.7% (19,026/23,863) always used face-masks in public areas. The frequency of handwashing with soap was relatively low (6424/23,863, 26.9% for >5 times/day); 72.4% (17,282/23,863) had frequently undertaken ≥2 of these 3 measures. COVID-19-related cognitive factors (perceptions on modes of transmission, permanent bodily damage, efficacy of personal or governmental preventive measures, nonavailability of vaccines and treatments) were significantly associated with preventive measures. Associations with frequent face-mask wearing were stronger than those with frequent home staying. CONCLUSIONS: University students had strong behavioral responses during the very early phase of the COVID-19 outbreak. Levels of personal prevention, especially frequent home staying and face-mask wearing, were high. Health promotion may modify cognitive factors. Some structural factors (eg, social distancing policy) might explain why the frequency of home staying was higher than that of handwashing. Other populations might have behaved similarly; however, such data were not available to us.


Subject(s)
COVID-19/prevention & control , Communicable Disease Control/methods , Disease Outbreaks/prevention & control , COVID-19/epidemiology , China/epidemiology , Cross-Sectional Studies , Female , Hand Disinfection , Humans , Male , Masks , Physical Distancing , Students , Surveys and Questionnaires , Universities
5.
PLoS One ; 17(11): e0274024, 2022.
Article in English | MEDLINE | ID: covidwho-2140502

ABSTRACT

To limit an infectious outbreak, the public must be informed about the infection risk and be motivated to comply with infection control measures. Perceiving a situation as threatening and seeing benefits to complying may be necessary to motivate for compliance. The current study used a preregistered survey experiment with a 2-by-2 between-subject design to investigate if emphasizing high infection risk and appealing to societal benefits impacted intention to comply with infection control measures. The results from a representative Norwegian sample (N = 2533) show that describing a high (as opposed to low) personal risk scenario had a small main effect on compliance. Further, appealing to public (as opposed to self-interested) benefits also had a small main effect. There was no interaction between risk scenario and motivational emphasis. The results suggest that to maximize compliance, information about disease outbreak should emphasize the individual risk of contracting the disease, and could also underline the public value of limiting infection spread. These findings can inform health authorities about the motives underlying compliance with infection control measures during an infectious disease outbreak.


Subject(s)
Influenza, Human , Pandemics , Humans , Pandemics/prevention & control , Influenza, Human/epidemiology , Infection Control , Disease Outbreaks/prevention & control , Surveys and Questionnaires
6.
Infect Dis Poverty ; 11(1): 114, 2022 Nov 24.
Article in English | MEDLINE | ID: covidwho-2139424

ABSTRACT

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant is highly transmissible with potential immune escape. Hence, control measures are continuously being optimized to guard against large-scale coronavirus disease 2019 (COVID-19) outbreaks. This study aimed to explore the relationship between the intensity of control measures in response to different SARS-CoV-2 variants and the degree of outbreak control at city level. METHODS: A retrospective study was conducted in 49 cities with COVID-19 outbreaks between January 2020 and June 2022. Epidemiological data on COVID-19 were extracted from the National Health Commission, People's Republic of China, and the population flow data were sourced from the Baidu migration data provided by the Baidu platform. Outbreak control was quantified by calculating the degree of infection growth and the time-varying reproduction number ([Formula: see text]). The intensity of the outbreak response was quantified by calculating the reduction in population mobility during the outbreak period. Correlation and regression analyses of the intensity of the control measures and the degree of outbreak control for the Omicron variant and non-Omicron mutants were conducted, respectively. RESULTS: Overall, 65 outbreaks occurred in 49 cities in China from January 2020 to June 2022. Of them, 66.2% were Omicron outbreaks and 33.8% were non-Omicron outbreaks. The intensity of the control measures was positively correlated with the degree of outbreak control (r = 0.351, P = 0.03). The degree of reduction in population mobility was negatively correlated with the Rt value (r = - 0.612, P < 0.01). Therefore, under the same control measure intensity, the number of new daily Omicron infections was 6.04 times higher than those attributed to non-Omicron variants, and the Rt value of Omicron outbreaks was 2.6 times higher than that of non-Omicron variants. In addition, the duration of non-Omicron variant outbreaks was shorter than that of the outbreaks caused by the Omicron variant (23.0 ± 10.7, 32.9 ± 16.3, t = 2.243, P = 0.031). CONCLUSIONS: Greater intensity of control measures was associated with more effective outbreak control. Thus, in response to the Omicron variant, the management to restrict population movement should be used to control its spread quickly, especially in the case of community transmission occurs widely. Faster than is needed for non-Omicron variants, and decisive control measures should be imposed and dynamically adjusted in accordance with the evolving epidemic situation.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Cities/epidemiology , COVID-19/epidemiology , Retrospective Studies , Disease Outbreaks/prevention & control
7.
BMJ Open Qual ; 11(4)2022 11.
Article in English | MEDLINE | ID: covidwho-2137805

ABSTRACT

BACKGROUND: In response to the severe hepatitis A outbreak that occurred in Michigan between August 2016 and September 2019, our multihospital health system implemented an electronic medical record (EMR)-based vaccination intervention across its nine emergency departments (EDs). The objectives were to explore the impact of this intervention on increasing vaccination rates among high-risk individuals and to assess the barriers to use of a computerised vaccine reminder system. METHODS: All patients who were 18 years or older were screened using an electronic nursing questionnaire. If a patient was at high risk based on the questionnaire, an electronic best practice advisory (BPA) would trigger and give the physician or advanced practice provider the option to order the hepatitis A vaccine. We explored the vaccination rates in the 24-month preintervention and the 18-month intervention periods. We then administered a survey to physicians, advanced practice providers and nurses evaluating their perceptions and barriers to use of the EMR intervention. RESULTS: During the preintervention period, 49 vaccines were ordered (5.5 per 100 000 patient visits) and 32 were administered (3.6 per 100 000 patient visits). During the intervention period, 574 865 patient visits (74.3%) were screened. 2494 vaccines (322 per 100 000 patient visits) were ordered, and 1205 vaccines (155 per 100 000 patients visits) were administered. Physicians and advanced practice providers were initially compliant with the BPA's use, but compliance declined over time. Surveys revealed that the major barrier to use was lack of time. CONCLUSIONS: EMR screening tools and BPAs can be used in the ED as an effective strategy to vaccinate high-risk individuals. This may be translatable to outbreaks of other vaccine-preventable illnesses like influenza, measles or SARS-CoV-2. Providing ongoing education about the public health initiative and giving feedback to physicians, advanced practice providers and nurses about tool compliance are needed to sustain the improvement over time.


Subject(s)
COVID-19 , Hepatitis A , Influenza Vaccines , Humans , Electronic Health Records , Hepatitis A/epidemiology , Hepatitis A/prevention & control , SARS-CoV-2 , Vaccination , Disease Outbreaks/prevention & control , Emergency Service, Hospital
9.
10.
J Formos Med Assoc ; 121(11): 2360-2364, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2121333

ABSTRACT

In Taiwan, 14,308 locally acquired COVID-19 cases among customers and employees in Sexy Tea shops were the first cases from May 9-August 28, 2021 (weeks 19-34). Nine weeks after the community spread of COVID-19 began, the proportion of people living with HIV (PLHIV) among the COVID-19 patients peaked at 35.7%, affecting 192 HIV patients, while the prevalence of HIV infection was 0.15%. In addition to a nationwide Level 3 epidemic alert, the Taiwan Centers for Disease Control (Taiwan CDC) launched four strategies to contain this outbreak among PLHIV in this prevaccine era, including improving the quality of contact tracing, delivering health information via peer navigators, expanding SARS-CoV-2 screening and encouraging vaccination, and addressing hesitancy. The outbreak of COVID-19 related to Alpha strain among PLHIV in 2021 ceased four weeks after peaking and lasted eight weeks.


Subject(s)
COVID-19 , HIV Infections , COVID-19/epidemiology , Disease Outbreaks/prevention & control , HIV Infections/complications , HIV Infections/epidemiology , Humans , SARS-CoV-2 , Taiwan/epidemiology , Tea
11.
Sci Rep ; 12(1): 19780, 2022 Nov 17.
Article in English | MEDLINE | ID: covidwho-2119290

ABSTRACT

Human behavioural changes are poorly understood, and this limitation has been a serious obstacle to epidemic forecasting. It is generally understood that people change their respective behaviours to reduce the risk of infection in response to the status of an epidemic or government interventions. We must first identify the factors that lead to such decision-making to predict these changes. However, due to an absence of a method to observe decision-making for future behaviour, understanding the behavioural responses to disease is limited. Here, we show that accommodation reservation data could reveal the decision-making process that underpins behavioural changes, travel avoidance, for reducing the risk of COVID-19 infections. We found that the motivation to avoid travel with respect to only short-term future behaviours dynamically varied and was associated with the outbreak status and/or the interventions of the government. Our developed method can quantitatively measure and predict a large-scale population's behaviour to determine the future risk of COVID-19 infections. These findings enable us to better understand behavioural changes in response to disease spread, and thus, contribute to the development of reliable long-term forecasting of disease spread.


Subject(s)
COVID-19 , Epidemics , Humans , COVID-19/epidemiology , Travel , Disease Outbreaks/prevention & control , Forecasting
12.
Mem Inst Oswaldo Cruz ; 117: e220114, 2022.
Article in English | MEDLINE | ID: covidwho-2119204

ABSTRACT

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected the maritime sector due to virus transmission onboard and traffic restrictions. However, reports of SARS-CoV-2 transmission on board have been mostly restricted to those occurring on cruise ships. OBJECTIVES: To report COVID-19 outbreaks in eight non-cruise vessels and discuss measures to prevent and control the onboard transmission of SARS-CoV-2. METHODS: We investigated outbreaks of COVID-19 on vessels anchoring in Baía de Todos-os-Santos, Salvador, Brazil, between February and November 2021. FINDINGS: Most vessels were cargo ships that had docked several times before anchoring in Salvador (five had docked in ≥ 9 ports). The crew ranged from 22 to 63 members. The infection attack rate on each vessel ranged from 9.7 to 88.9%. The risk of symptomatic infection largely varied among the crew of each vessel (0 to 91.6%). Overall, the risk of developing COVID-19 signs and symptoms was lower among crew members vaccinated (age-adjusted risk ratio: 0.19; 95% confidence interval 0.06-0.65). SARS-CoV-2 variants not previously identified in Salvador were detected (C.14, B.1.617.2 and B.1.351). MAIN CONCLUSIONS: Despite maritime guidelines to avert COVID-19 on board, outbreaks have happened. The multiple stopovers of non-cruise vessels during their routes may contribute to the spread of SARS-CoV-2 variants worldwide. Reducing the onboard transmission of SARS-CoV-2 depends on joint efforts by the crew and local health authorities and, equally important, achieving high vaccination coverage to prevent infections and illness.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Brazil/epidemiology , Disease Outbreaks/prevention & control
13.
Epidemiol Infect ; 150: e182, 2022 Nov 17.
Article in English | MEDLINE | ID: covidwho-2116432

ABSTRACT

Mass gatherings (MG) present a number of challenges to public health authorities and governments across the world with sporting events, tournaments, music festivals, religious gatherings and all other MG having historically posed a risk to the spread and amplification of a range of infectious diseases. Transmission of gastrointestinal, respiratory, waterborne and sexually transmitted infectious diseases pose a particular risk: all have been linked to MG events [-]. Infection risk often depends on the nature of the mass gathering, and on the profile and behaviour of its participants. The interaction between environmental, psychological, biological and social factors plays a vital part. The risk of outbreaks particularly as a result of respiratory transmission remains high at MG, with the majority of outbreaks over the last two decades resulting from a variety of respiratory and vaccine preventable pathogens [-]. Concerns about the spread of infectious diseases at MG are often focussed on crowding, lack of sanitation and the mixing of population groups from different places. Sporting events, which have in recent decades become more complex and international in nature, pose a challenge to the control of communicable disease transmission []. Despite this, large scale outbreaks at sporting events have been rare in recent decades, particularly since the rise of more robust public health planning, prevention, risk assessment and improved health infrastructures in host countries [].


Subject(s)
COVID-19 , Communicable Diseases , United States , Humans , COVID-19/epidemiology , Mass Gatherings , Pandemics/prevention & control , Disease Outbreaks/prevention & control , Communicable Diseases/epidemiology
14.
BMC Infect Dis ; 22(1): 845, 2022 Nov 12.
Article in English | MEDLINE | ID: covidwho-2115862

ABSTRACT

BACKGROUND: From 20 July to 26 August 2021, local outbreaks of COVID-19 occurred in Nanjing City and Yangzhou City (Jiangsu Province, China). We analyzed the characteristics of these outbreaks in an effort to develop specific and effective intervention strategies. METHODS: Publicly available data on the characteristics of the COVID-19 outbreaks in Jiangsu Province were collected. Logistic regression was used to assess the association of age and sex with clinical severity. Analysis of onset dates, generation time distributions, and locations were used to estimate the mean transmission distance. A branching process model was used to evaluate different management strategies. RESULTS: From 20 July to 26 August 2021, 820 patients were diagnosed with COVID-19 in Jiangsu Province, with 235 patients (28.7%) from Nanjing, 570 (69.5%) from Yangzhou, and 15 (1.8%) from other cities. Overall, 57.9% of the patients were female, 13.7% were under 20 years-old, and 58.3% had moderate disease status. The mean transmission distance was 4.12 km, and closed-loop management of the area within 2.23 km of cases seemed sufficient to control an outbreak. The model predicted that the cumulative cases in Yangzhou would increase from 311 to 642 if the interval between rounds of nucleic acid amplification testing (NAAT) increased from 1 to 6 days. It also predicted there would be 44.7% more patients if the NAAT started 10 days (rather than 0 days) after diagnosis of the first case. The proportion of cases detected by NAAT would increase from 11.16 to 44.12% when the rounds of NAAT increased from 1 to 7 within 17 days. When the effective vaccine coverage was 50%, the outbreak would be controlled even when using the most relaxed non-pharmaceutical interventions. CONCLUSIONS: The model predicted that a timely closed-loop management of a 2.23 km area around positive COVID-19 cases was sufficient to control the outbreak. Prompt serial NAAT is likely to contain an outbreak quickly, and our model results indicated that three rounds of NAAT sufficiently controlled local transmission. Trial registration We did not involve clinical trial.


Subject(s)
COVID-19 , Nucleic Acids , Humans , Female , Young Adult , Adult , Male , COVID-19/epidemiology , SARS-CoV-2 , Disease Outbreaks/prevention & control , China/epidemiology
15.
Pan Afr Med J ; 42(Suppl 1): 8, 2022.
Article in English | MEDLINE | ID: covidwho-2110978

ABSTRACT

The vulnerable populations in the protracted humanitarian crisis in South Sudan are faced with constrained access to health services and frequent disease outbreaks. Here, we describe the experiences of emergency mobile medical teams (eMMT) assembled by the World Health Organization (WHO) South Sudan to respond to public health emergencies. Interventions: the eMMTs, multidisciplinary teams based at national, state and county levels, are rapidly deployed to conduct rapid assessments, outbreak investigations, and initiate public health response during acute emergencies. The eMMTs were deployed to locations affected by flooding, conflicts, famine, and disease outbreaks. We reviewed records of deployment reports, outreach and campaign registers, and analyzed the key achievements of the eMMTs for 2017 through 2020. Achievements: the eMMTs investigated disease outbreaks including cholera, measles, Rift Valley fever and coronavirus disease (COVID-19) in 13 counties, conducted mobile outreaches in emergency locations in 38 counties (320,988 consultations conducted), trained 550 healthcare workers including rapid response teams, and supported reactive measles vaccination campaigns in seven counties [148,726, (72-125%) under-5-year-old children vaccinated] and reactive oral cholera vaccination campaigns in four counties (355,790 vaccinated). The eMMT is relevant in humanitarian settings and can reduce excess morbidity and mortality and fill gaps that routine health facilities and health partners could not bridge. However, the scope of the services offered needs to be broadened to include mental and psychosocial care and a strategy for ensuring continuity of vaccination services and management of chronic conditions after the mobile outreach is instituted.


Subject(s)
COVID-19 , Cholera , Measles , Child, Preschool , Cholera/epidemiology , Disease Outbreaks/prevention & control , Emergencies , Humans , Immunization Programs , Measles/epidemiology , Measles/prevention & control , South Sudan/epidemiology
16.
Viruses ; 14(11)2022 Nov 14.
Article in English | MEDLINE | ID: covidwho-2110281

ABSTRACT

Hong Kong SAR has adopted universal masking, social distancing, testing of all symptomatic and high-risk groups for isolation of confirmed cases in healthcare facilities, and quarantine of contacts as epidemiological control measures without city lockdown or border closure. These measures successfully suppressed the community transmission of pre-Omicron SARS-CoV-2 variants or lineages during the first to the fourth wave. No nosocomial SARS-CoV-2 infection was documented among healthcare workers in the first 300 days. The strategy of COVID-19 containment was adopted to provide additional time to achieve population immunity by vaccination. The near-zero COVID-19 situation for about 8 months in 2021 did not enable adequate immunization of the eligible population. A combination of factors was identified, especially population complacency associated with the low local COVID-19 activity, together with vaccine hesitancy. The importation of the highly transmissible Omicron variant kickstarted the fifth wave of COVID-19, which could no longer be controlled by our initial measures. The explosive fifth wave, which was partially contributed by vertical airborne transmission in high-rise residential buildings, resulted in over one million cases of infection. In this review, we summarize the epidemiology of COVID-19 and the infection control and public health measures against the importation and dissemination of SARS-CoV-2 until day 1000.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Disease Outbreaks/prevention & control , Hong Kong/epidemiology , Infection Control
19.
PLoS One ; 17(11): e0274407, 2022.
Article in English | MEDLINE | ID: covidwho-2109309

ABSTRACT

Since early March 2020, government agencies have utilized a wide variety of non-pharmaceutical interventions to mitigate the spread of COVID-19 and have struggled to determine when it is appropriate to return to in-person activities after an outbreak is detected. At many universities, fundamental issues related to understanding the spread of the disease (e.g. the transmission rate), the ability of administrators to respond quickly enough by closing when there is a sudden rise in cases, and how to make a decision on when to reopen remains a concern. Surveillance testing strategies have been implemented in some places, and those test outcomes have dictated whether to reopen, to simultaneously monitor community spread, and/or to isolate discovered cases. However, the question remains as to when it is safe to reopen and how much testing is required to remain safely open while keeping infection numbers low. Here, we propose an extension of the classic SIR model to investigate reopening strategies for a fixed testing strategy, based on feedback from testing results. Specifically, we close when a predefined proportion of the population becomes infected, and later reopen when that infected proportion decreases below a predefined threshold. A valuable outcome of our approach is that our reopening strategies are robust to variation in almost all model parameters, including transmission rates, which can be extremely difficult to determine as they typically differ between variants, location, vaccination status, etc. Thus, these strategies can be, in theory, translated over to new variants in different regions of the world. Examples of robust feedback strategies for high disease transmission and a fixed testing capacity include (1) a single long lock down followed by a single long in-person period, and (2) multiple shorter lock downs followed by multiple shorter in-person periods. The utility of this approach of having multiple strategies is that administrators of universities, schools, business, etc. can use a strategy that is best adapted for their own functionality.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Communicable Disease Control/methods , Schools , Disease Outbreaks/prevention & control , Universities
20.
Vaccine ; 40(46): 6664-6669, 2022 Nov 02.
Article in English | MEDLINE | ID: covidwho-2106124

ABSTRACT

BACKGROUND: Elderly people in long-term care facilities (LTCF) are at higher risk for (severe) COVID-19, yet evidence of vaccine effectiveness (VE) in this population is scarce. In November 2021 (Delta period), a COVID-19 outbreak occurred at a LTCF in the Netherlands, continuing despite measures and booster vaccination campaign. We investigated the outbreak to assess VE of primary COVID-19 vaccination against SARS-CoV-2 infection and mortality, and to describe the impact of the booster vaccination. METHODS: We calculated attack rate (AR) and case fatality (CF) per vaccination status (unvaccinated, primarily vaccinated and boostered). We calculated VE - at on average 6 months after vaccination - as 1- risk ratio (RR) using the crude risk ratio (RR) with 95% confidence intervals (CI) for the association between vaccination status (primary vaccination versus unvaccinated) and outcomes (SARS-CoV-2 infection and mortality < 30 days after testing positive for SARS-CoV-2). RESULTS: The overall AR was 67% (70/105). CF was 33% (2/6) among unvaccinated cases, 12% among primarily vaccinated (7/58) and 0% (0/5) among boostered. The VE of primary vaccination was 17% (95% CI -28%; 46%) against SARS-CoV-2 infection and 70% (95% CI -44%; 96%) against mortality. Among boostered residents (N = 55), there were 25 cases in the first week after receiving the booster dose, declining to 5 in the second and none in the third week. CONCLUSION: VE of primary vaccination in residents of LTCF was very low against SARS-CoV-2 infection and moderate against mortality. There were few cases at 2 weeks after the booster dose and no deaths, despite the presence of susceptible residents. These data are consistent with the positive impact of the booster vaccination in curbing transmission. Timely booster vaccination in residents of LTCF is therefore important.


Subject(s)
COVID-19 , Humans , Aged , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Vaccine Efficacy , SARS-CoV-2 , Immunization Programs , Disease Outbreaks/prevention & control
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