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1.
PLoS Comput Biol ; 18(8): e1010465, 2022 08.
Article in English | MEDLINE | ID: covidwho-2021469

ABSTRACT

Reported COVID-19 cases and deaths provide a delayed and incomplete picture of SARS-CoV-2 infections in the United States (US). Accurate estimates of both the timing and magnitude of infections are needed to characterize viral transmission dynamics and better understand COVID-19 disease burden. We estimated time trends in SARS-CoV-2 transmission and other COVID-19 outcomes for every county in the US, from the first reported COVID-19 case in January 13, 2020 through January 1, 2021. To do so we employed a Bayesian modeling approach that explicitly accounts for reporting delays and variation in case ascertainment, and generates daily estimates of incident SARS-CoV-2 infections on the basis of reported COVID-19 cases and deaths. The model is freely available as the covidestim R package. Nationally, we estimated there had been 49 million symptomatic COVID-19 cases and 404,214 COVID-19 deaths by the end of 2020, and that 28% of the US population had been infected. There was county-level variability in the timing and magnitude of incidence, with local epidemiological trends differing substantially from state or regional averages, leading to large differences in the estimated proportion of the population infected by the end of 2020. Our estimates of true COVID-19 related deaths are consistent with independent estimates of excess mortality, and our estimated trends in cumulative incidence of SARS-CoV-2 infection are consistent with trends in seroprevalence estimates from available antibody testing studies. Reconstructing the underlying incidence of SARS-CoV-2 infections across US counties allows for a more granular understanding of disease trends and the potential impact of epidemiological drivers.


Subject(s)
COVID-19 , Epidemics , Bayes Theorem , COVID-19/epidemiology , Humans , SARS-CoV-2 , Seroepidemiologic Studies , United States/epidemiology
2.
Clin Infect Dis ; 2022 Jun 20.
Article in English | MEDLINE | ID: covidwho-1901137

ABSTRACT

BACKGROUND: Both SARS-CoV-2 infection and COVID-19 vaccination contribute to population-level immunity against SARS-CoV-2. This study estimates the immunological exposure and effective protection against future SARS-CoV-2 infection in each US state and county over 2020-2021, and how this changed with the introduction of the Omicron variant. METHODS: We used a Bayesian model to synthesize estimates of daily SARS-CoV-2 infections, vaccination data and estimates of the relative rates of vaccination conditional on infection status to estimate the fraction of the population with (i) immunological exposure to SARS-CoV-2 (ever infected with SARS-CoV-2 and/or received one or more doses of a COVID-19 vaccine), (ii) effective protection against infection, and (iii) effective protection against severe disease, for each US state and county from January 1, 2020, to December 1, 2021. RESULTS: The estimated percentage of the US population with a history of SARS-CoV-2 infection or vaccination as of December 1, 2021, was 88.2% (95% Credible Interval (CrI): 83.6%-93.5%). Accounting for waning and immune escape, effective protection against the Omicron variant on December 1, 2021, was 21.8% (95%CrI: 20.7%-23.4%) nationally and ranged between 14.4% (95%CrI: 13.2%-15.8%, West Virginia) to 26.4% (95%CrI: 25.3%-27.8%, Colorado). Effective protection against severe disease from Omicron was 61.2% (95%CrI: 59.1%-64.0%) nationally and ranged between 53.0% (95%CrI: 47.3%-60.0%, Vermont) and 65.8% (95%CrI: 64.9%-66.7%, Colorado). CONCLUSIONS: While over four-fifths of the US population had prior immunological exposure to SARS-CoV-2 via vaccination or infection on December 1, 2021, only a fifth of the population was estimated to have effective protection against infection with the immune-evading Omicron variant.

3.
Influenza Other Respir Viruses ; 16(4): 617-620, 2022 07.
Article in English | MEDLINE | ID: covidwho-1891573

ABSTRACT

We used a validated proxy of respiratory syncytial virus (RSV) activity in the United States (Google search data) to evaluate the onsets of RSV epidemics in 2021 and 2016-2019. Despite the unusual out-of-season summer timing, the relative timing of RSV epidemics between states in 2021 shared a similar spatial pattern with typical winter RSV seasons. Our results suggest that the onset of RSV epidemics in Florida can serve as a baseline to adjust the initiation of prophylaxis administration and clinical trials in other states regardless of the seasonality of RSV epidemics.


Subject(s)
Epidemics , Respiratory Syncytial Virus Infections , Respiratory Syncytial Virus, Human , Humans , Seasons , United States/epidemiology
4.
BMJ ; 377: e071113, 2022 05 24.
Article in English | MEDLINE | ID: covidwho-1861604

ABSTRACT

OBJECTIVE: To examine the relative effectiveness of a fourth dose of the Pfizer-BioNTech mRNA (BNT162b2) vaccine compared with three vaccine doses over the span of 10 weeks. DESIGN: Retrospective, test negative, case-control study, with a matched analysis and an unmatched multiple tests analysis. SETTING: Nationally centralised database of Maccabi Healthcare Services, an Israeli national health fund for 2.5 million people; from 10 January 2022 (seven days after the fourth dose was first given to eligible individuals) to 13 March 2022, an omicron dominant period in Israel. PARTICIPANTS: 97 499 Maccabi Healthcare Services members aged 60 years and older, who were eligible to receive a fourth vaccine dose and obtained at least one polymerase chain reaction (PCR) test during the study. MAIN OUTCOME MEASURES: Breakthrough SARS-CoV-2 infection, defined as a positive PCR test performed seven or more days after inoculation with the BNT162b2 vaccine; and breakthrough SARS-CoV-2 infection resulting in severe covid-19 disease, defined as hospital admission or death related to covid-19. RESULTS: 27 876 participants received the fourth BNT162b2 vaccine dose and 69 623 received three doses only. Of 106 participants who died during the follow-up period, 77 had had their third doses only and 23 had had their fourth doses during the first three weeks after inoculation. In the first three weeks, a fourth dose provided additional protection against both SARS-CoV-2 infection and severe disease relative to three doses of the vaccine. However, relative vaccine effectiveness against infection quickly decreased over time, peaking during the third week at 65.1% (95% confidence interval 63.0% to 67.1%) and falling to 22.0% (4.9% to 36.1%) by the end of the 10 week follow-up period. Unlike relative effectiveness against SARS-CoV-2 infection, the relative effectiveness of a fourth dose against severe covid-19 was maintained at a high level (>72%) throughout follow-up. However, severe disease was a relatively rare event, occurring in <1% of study participants who received four doses or three doses only. CONCLUSIONS: A fourth dose of the BNT162b2 vaccine appears to have provided additional protection against both SARS-CoV-2 infection and severe covid-19 disease relative to three vaccine doses. However, relative effectiveness of the fourth dose against infection appears to wane sooner than that of the third dose.


Subject(s)
COVID-19 Vaccines , COVID-19 , Aged , BNT162 Vaccine , COVID-19/epidemiology , COVID-19/prevention & control , Case-Control Studies , Humans , Israel/epidemiology , Middle Aged , Retrospective Studies , SARS-CoV-2
5.
Commun Biol ; 5(1): 439, 2022 05 11.
Article in English | MEDLINE | ID: covidwho-1839575

ABSTRACT

SARS-CoV-2 variants shaped the second year of the COVID-19 pandemic and the discourse around effective control measures. Evaluating the threat posed by a new variant is essential for adapting response efforts when community transmission is detected. In this study, we compare the dynamics of two variants, Alpha and Iota, by integrating genomic surveillance data to estimate the effective reproduction number (Rt) of the variants. We use Connecticut, United States, in which Alpha and Iota co-circulated in 2021. We find that the Rt of these variants were up to 50% larger than that of other variants. We then use phylogeography to show that while both variants were introduced into Connecticut at comparable frequencies, clades that resulted from introductions of Alpha were larger than those resulting from Iota introductions. By monitoring the dynamics of individual variants throughout our study period, we demonstrate the importance of routine surveillance in the response to COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , Genomics , Humans , Pandemics , SARS-CoV-2/genetics , United States/epidemiology
6.
Cell Rep Med ; 3(4): 100583, 2022 04 19.
Article in English | MEDLINE | ID: covidwho-1735052

ABSTRACT

The SARS-CoV-2 Delta variant rose to dominance in mid-2021, likely propelled by an estimated 40%-80% increased transmissibility over Alpha. To investigate if this ostensible difference in transmissibility is uniform across populations, we partner with public health programs from all six states in New England in the United States. We compare logistic growth rates during each variant's respective emergence period, finding that Delta emerged 1.37-2.63 times faster than Alpha (range across states). We compute variant-specific effective reproductive numbers, estimating that Delta is 63%-167% more transmissible than Alpha (range across states). Finally, we estimate that Delta infections generate on average 6.2 (95% CI 3.1-10.9) times more viral RNA copies per milliliter than Alpha infections during their respective emergence. Overall, our evidence suggests that Delta's enhanced transmissibility can be attributed to its innate ability to increase infectiousness, but its epidemiological dynamics may vary depending on underlying population attributes and sequencing data availability.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , Humans , New England/epidemiology , Public Health , SARS-CoV-2/genetics
7.
JAMA Netw Open ; 4(12): e2141779, 2021 12 01.
Article in English | MEDLINE | ID: covidwho-1576027

ABSTRACT

Importance: Respiratory syncytial virus (RSV) is a leading cause of hospitalizations in young children. RSV largely disappeared in 2020 owing to precautions taken because of the COVID-19 pandemic. Estimating the timing and intensity of the reemergence of RSV and the age groups affected is crucial for planning for the administration of prophylactic antibodies and anticipating hospital capacity. Objective: To examine the association of different factors, including mitigation strategies, duration of maternal-derived immunity, and importation of external infections, with the dynamics of reemergent RSV epidemics. Design, Setting, and Participants: This simulation modeling study used mathematical models to reproduce the annual epidemics of RSV before the COVID-19 pandemic in New York and California. These models were modified to project the trajectory of RSV epidemics from 2020 to 2025 under different scenarios with varying stringency of mitigation measures for SARS-CoV-2. Simulations also evaluated factors likely to affect the reemergence of RSV epidemics, including introduction of the virus from out-of-state sources and decreased transplacentally acquired immunity in infants. Models using parameters fitted to similar inpatient data sets from Colorado and Florida were used to illustrate these associations in populations with biennial RSV epidemics and year-round RSV circulation, respectively. Statistical analysis was performed from February to October 2021. Main Outcomes and Measures: The primary outcome of this study was defined as the estimated number of RSV hospitalizations each month in the entire population. Secondary outcomes included the age distribution of hospitalizations among children less than 5 years of age, incidence of any RSV infection, and incidence of RSV lower respiratory tract infection. Results: Among a simulated population of 19.45 million people, virus introduction from external sources was associated with the emergence of the spring and summer epidemic in 2021. There was a tradeoff between the intensity of the spring and summer epidemic in 2021 and the intensity of the epidemic in the subsequent winter. Among children 1 year of age, the estimated incidence of RSV hospitalizations was 707 per 100 000 children per year in the 2021 and 2022 RSV season, compared with 355 per 100 000 children per year in a typical RSV season. Conclusions and Relevance: This simulation modeling study found that virus introduction from external sources was associated with the spring and summer epidemics in 2021. These findings suggest that pediatric departments should be alert to large RSV outbreaks in the coming seasons, the intensity of which could depend on the size of the spring and summer epidemic in that location. Enhanced surveillance is recommended for both prophylaxis administration and hospital capacity management.


Subject(s)
COVID-19/epidemiology , Communicable Diseases, Emerging/epidemiology , Pandemics , Respiratory Syncytial Virus Infections/epidemiology , Age Distribution , Child, Preschool , Epidemiological Models , Hospitalization/statistics & numerical data , Humans , Incidence , Infant , Infectious Disease Transmission, Vertical , Physical Distancing , SARS-CoV-2 , Seasons , United States/epidemiology
8.
JAMA Intern Med ; 182(2): 179-184, 2022 02 01.
Article in English | MEDLINE | ID: covidwho-1540033

ABSTRACT

Importance: With the evidence of waning immunity of the mRNA vaccine BNT162b2 (Pfizer-BioNTech), a nationwide third-dose (booster) vaccination campaign was initiated in Israel during August 2021; other countries have begun to administer a booster shot as well. Objective: To evaluate the initial short-term additional benefit of a 3-dose vs a 2-dose regimen against infection of SARS-CoV-2. Design, Setting, and Participants: This preliminary retrospective case-control study used 2 complementary approaches: a test-negative design and a matched case-control design. Participants were included from the national centralized database of Maccabi Healthcare Services, an Israeli healthcare maintenance organization covering 2.5 million members. Data were collected between March 1, 2020, and October 4, 2021, and analyses focused on the period from August 1, 2021, to October 4, 2021, because the booster dose was widely administered from August 1 onward. Exposures: Either 2 doses or 3 doses of the BNT162b2 vaccine. Main Outcomes and Measures: The reduction in the odds of a positive SARS-CoV-2 polymerase chain reaction (PCR) test at different time intervals following receipt of the booster dose (0-6, 7-13, 14-20, 21-27, and 28-65 days) compared with receiving only 2 doses. Results: The study population included 306 710 members of Maccabi Healthcare Services who were 40 years and older (55% female) and received either 2 or 3 doses of the BNT162b2 vaccine and did not have a positive PCR test result for SARS-CoV-2 prior to the start of the follow-up period. During this period, there were 500 232 PCR tests performed, 227 380 among those who received 2 doses and 272 852 among those who received 3 doses, with 14 989 (6.6%) and 4941 (1.8%) positive test results in each group, respectively. Comparing those who received a booster and those who received 2 doses, there was an estimated odds ratio of 0.14 (95% CI, 0.13-0.15) 28 to 65 days following receipt of the booster (86% reduction in the odds of testing positive for SARS-CoV-2). Conclusion and Relevance: Previous studies have demonstrated that vaccine-derived protection against SARS-CoV-2 wanes over time. In this case-control analysis, we showed an association between receipt of the booster dose and a reduction in the odds of testing positive for SARS-CoV-2, potentially counteracting waning immunity in the short term. Further monitoring of data from this population is needed to determine the duration of immunity following the booster.


Subject(s)
BNT162 Vaccine/therapeutic use , COVID-19 Vaccines/therapeutic use , COVID-19/diagnosis , COVID-19/prevention & control , SARS-CoV-2/isolation & purification , Adult , Case-Control Studies , Comparative Effectiveness Research , Female , Humans , Incidence , Male , Retrospective Studies , Time Factors
9.
Am J Epidemiol ; 190(9): 1908-1917, 2021 09 01.
Article in English | MEDLINE | ID: covidwho-1172642

ABSTRACT

Estimates of the reproductive number for novel pathogens, such as severe acute respiratory syndrome coronavirus 2, are essential for understanding the potential trajectory of epidemics and the levels of intervention that are needed to bring the epidemics under control. However, most methods for estimating the basic reproductive number (R0) and time-varying effective reproductive number (Rt) assume that the fraction of cases detected and reported is constant through time. We explored the impact of secular changes in diagnostic testing and reporting on estimates of R0 and Rt using simulated data. We then compared these patterns to data on reported cases of coronavirus disease 2019 and testing practices from different states in the United States from March 4, 2020, to August 30, 2020. We found that changes in testing practices and delays in reporting can result in biased estimates of R0 and Rt. Examination of changes in the daily numbers of tests conducted and the percentages of patients who tested positive might be helpful for identifying the potential direction of bias. Changes in diagnostic testing and reporting processes should be monitored and taken into consideration when interpreting estimates of the reproductive number of coronavirus disease.


Subject(s)
COVID-19/diagnosis , COVID-19/epidemiology , Basic Reproduction Number , COVID-19/transmission , Computer Simulation , Diagnostic Techniques and Procedures , Documentation , Epidemics , Humans , Models, Theoretical , Reproducibility of Results , SARS-CoV-2 , United States/epidemiology
10.
JAMA Intern Med ; 180(10): 1336-1344, 2020 10 01.
Article in English | MEDLINE | ID: covidwho-624433

ABSTRACT

Importance: Efforts to track the severity and public health impact of coronavirus disease 2019 (COVID-19) in the United States have been hampered by state-level differences in diagnostic test availability, differing strategies for prioritization of individuals for testing, and delays between testing and reporting. Evaluating unexplained increases in deaths due to all causes or attributed to nonspecific outcomes, such as pneumonia and influenza, can provide a more complete picture of the burden of COVID-19. Objective: To estimate the burden of all deaths related to COVID-19 in the United States from March to May 2020. Design, Setting, and Population: This observational study evaluated the numbers of US deaths from any cause and deaths from pneumonia, influenza, and/or COVID-19 from March 1 through May 30, 2020, using public data of the entire US population from the National Center for Health Statistics (NCHS). These numbers were compared with those from the same period of previous years. All data analyzed were accessed on June 12, 2020. Main Outcomes and Measures: Increases in weekly deaths due to any cause or deaths due to pneumonia/influenza/COVID-19 above a baseline, which was adjusted for time of year, influenza activity, and reporting delays. These estimates were compared with reported deaths attributed to COVID-19 and with testing data. Results: There were approximately 781 000 total deaths in the United States from March 1 to May 30, 2020, representing 122 300 (95% prediction interval, 116 800-127 000) more deaths than would typically be expected at that time of year. There were 95 235 reported deaths officially attributed to COVID-19 from March 1 to May 30, 2020. The number of excess all-cause deaths was 28% higher than the official tally of COVID-19-reported deaths during that period. In several states, these deaths occurred before increases in the availability of COVID-19 diagnostic tests and were not counted in official COVID-19 death records. There was substantial variability between states in the difference between official COVID-19 deaths and the estimated burden of excess deaths. Conclusions and Relevance: Excess deaths provide an estimate of the full COVID-19 burden and indicate that official tallies likely undercount deaths due to the virus. The mortality burden and the completeness of the tallies vary markedly between states.


Subject(s)
Betacoronavirus/isolation & purification , Coronavirus Infections , Influenza, Human , Mortality/trends , Pandemics/statistics & numerical data , Pneumonia, Viral , Pneumonia , Adult , COVID-19 , COVID-19 Testing , Cause of Death , Clinical Laboratory Techniques/methods , Clinical Laboratory Techniques/statistics & numerical data , Coronavirus Infections/diagnosis , Coronavirus Infections/mortality , Cost of Illness , Female , Humans , Influenza, Human/diagnosis , Influenza, Human/mortality , Male , Pneumonia/diagnosis , Pneumonia/etiology , Pneumonia/mortality , Pneumonia, Viral/diagnosis , Pneumonia, Viral/mortality , SARS-CoV-2
11.
Clin Infect Dis ; 72(9): 1493-1496, 2021 05 04.
Article in English | MEDLINE | ID: covidwho-614249

ABSTRACT

Asymptomatic infection occurs for numerous respiratory viral diseases, including influenza and coronavirus disease 2019 (COVID-19). We seek to clarify confusion in 3 areas: age-specific risks of transmission and/or disease; various definitions for the COVID-19 "mortality rate," each useful for specific purposes; and implications for student return strategies from preschool through university settings.


Subject(s)
COVID-19 , Influenza, Human , Asymptomatic Infections , Child, Preschool , Humans , Influenza, Human/epidemiology , SARS-CoV-2 , Schools
13.
Cell ; 181(5): 990-996.e5, 2020 05 28.
Article in English | MEDLINE | ID: covidwho-60444

ABSTRACT

The novel coronavirus SARS-CoV-2 was first detected in the Pacific Northwest region of the United States in January 2020, with subsequent COVID-19 outbreaks detected in all 50 states by early March. To uncover the sources of SARS-CoV-2 introductions and patterns of spread within the United States, we sequenced nine viral genomes from early reported COVID-19 patients in Connecticut. Our phylogenetic analysis places the majority of these genomes with viruses sequenced from Washington state. By coupling our genomic data with domestic and international travel patterns, we show that early SARS-CoV-2 transmission in Connecticut was likely driven by domestic introductions. Moreover, the risk of domestic importation to Connecticut exceeded that of international importation by mid-March regardless of our estimated effects of federal travel restrictions. This study provides evidence of widespread sustained transmission of SARS-CoV-2 within the United States and highlights the critical need for local surveillance.


Subject(s)
Betacoronavirus/genetics , Coronavirus Infections/transmission , Pneumonia, Viral/transmission , Travel , Betacoronavirus/isolation & purification , COVID-19 , Connecticut/epidemiology , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Epidemiological Monitoring , Humans , Likelihood Functions , Pandemics , Phylogeny , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , SARS-CoV-2 , Travel/legislation & jurisprudence , United States/epidemiology , Washington/epidemiology
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