The impact of vaccination on COVID-19 outbreaks in the United States

Moghadas, Seyed M.; Vilches, Thomas N.; Zhang, Kevin; Wells, Chad R.; Shoukat, Affan; Singer, Burton H.; Meyers, Lauren Ancel; Neuzil, Kathleen M.; Langley, Joanne M.; Fitzpatrick, Meagan C.; Galvani, Alison P.

doi:10.1101/2020.11.27.20240051

Cited by 202 publications

(188 citation statements)

References 40 publications

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“…These conclusions are consistent with previous work that has optimized vaccine allocation assuming a single dose [23,24,11]. In agreement with others [25,26,27], our results show the absolute necessity to keep social distancing interventions in place: if social distancing interventions are lax, or if the vaccine is not rolled out fast enough, then our results show that the effect of vaccination will be limited, and that the current wave of infections will be over long before 12 vaccine campaigns finish.…”

Section: Discussionsupporting

confidence: 93%

Optimizing vaccine allocation for COVID-19 vaccines: potential role of single-dose vaccination

Matrajt

Eaton

Leung

et al. 2021

Preprint

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Most COVID-19 vaccines require two doses, and current vaccine prioritization guidelines for COVID-19 vaccines assume full-dose vaccine deployment. However in the context of limited vaccine supply and an expanding pandemic, policymakers are considering single-dose vaccination as an alternative strategy. Using a mathematical model combined with optimization algorithms, we determined the optimal allocation with one and two doses of vaccine to minimize five metrics of disease burden under various degrees of viral transmission. Under low transmission, we show that the optimal allocation of vaccine critically depends on the level of single-dose efficacy (SDE). If the SDE is high, single-dose vaccination is optimal, preventing up to 36% more deaths than a strategy prioritizing full-dose vaccination for older adults first. With low or moderate SDE, mixed vaccination campaigns with coverage of all older adults with one dose are optimal. However, with modest or high transmission, vaccinating older adults first with two doses is best, preventing up to 41% more deaths than a single-dose vaccination given across all populations. Further, we show that maintaining social distancing interventions and speedy deployment are key for effective vaccination campaigns. Our work suggests that it is imperative to determine the efficacy and durability of single-dose vaccines, as mixed or single-dose vaccination campaigns may have the potential to contain the pandemic much more quickly.

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Section: Discussionsupporting

confidence: 93%

Optimizing vaccine allocation for COVID-19 vaccines: potential role of single-dose vaccination

Matrajt

Eaton

Leung

et al. 2021

Preprint

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“…Previous modeling of vaccines looked into a possible impact of vaccines on the outbreak in the US. According to this study, vaccine coverage that will reach 40% in the American population within nearly a year will mitigate morbidity effectively, even though this is far from reaching herd immunity (7). Nevertheless, the modeling ignores current trends in the dynamic of COVID-19 in the US, except for the cumulative incidence of the disease so far.…”

Section: Main Textmentioning

confidence: 99%

First indication of the effect of COVID-19 vaccinations on the course of the outbreak in Israel

De-Leon

Calderon‐Margalit

Pederiva

et al. 2021

Preprint

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Concomitantly with rolling out its rapid COVID-19 vaccine program, Israel is experiencing its third, and so far largest, surge in morbidity. We aimed to estimate whether the high vaccine coverage among individuals aged over 60 years old creates an observable change in disease dynamics. Using observed and simulated data, we suggest that the shape of the outbreak as measured by daily new moderate and severe cases, and in particular of patients aged over 60, has changed because of vaccination, bringing the decline in new moderate and severe cases earlier than expected, by about a week. Our analyses is consistent with the assumption that vaccination lead to higher than 50% protection in preventing clinical disease and with at least some effectiveness in blocking transmission of elderly population, and supports the importance of prioritizing vulnerable population . This is the first indication of the effectivity of COVID-19 vaccine in changing the course of an ongoing pandemic outbreak.

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“…We assumed that 80% of individuals 50 years and older, and 22% of adults aged 18-49 years would be vaccinated, resulting in an overall vaccine coverage of 40% among adults within 1 year. 30 The vaccine efficacy against developing symptomatic or severe disease post-vaccination was 95%, based on the results of phase III clinical trials. 9,10 We also assumed that vaccine efficacy against infection was 50% lower than the efficacy against disease, but also considered a scenario with the same efficacy of 95% as a sensitivity analysis (Appendix).…”

Section: Methodsmentioning

confidence: 99%

Simulated identification of silent COVID-19 infections among children and estimated future infection rates with vaccination

Moghadas

Fitzpatrick

Shoukat

et al. 2021

Preprint

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ImportanceA significant proportion of COVID-19 transmission occurs silently during the pre-symptomatic and asymptomatic stages of infection. Children, while being important drivers of silent transmission, are not included in COVID-19 vaccination campaigns given their exclusion from clinical trials thus far.ObjectiveTo investigate the impact of a targeted approach to identifying silent infections among children as a proxy for their vaccination.DesignThis study used an age-structured disease transmission model to simulate the synergistic impact of interventions in reducing attack rates over the course of one year.SettingA synthetic population representative of the demographics of the United States (US).ParticipantsSix age groups of 0-4, 5-10, 11-18, 19-49, 50-64, 65+ years old, stratified for their population size based on US census data.ExposuresVaccination of adults, self-isolation of all symptomatic cases within 24 hours of symptom onset, and detection of silent infections.Main Outcomes and MeasuresVaccination of adults was implemented to reach a 40% coverage over the course of one year with a vaccine efficacy of 95% against symptomatic and severe COVID-19. Without vaccination of children, we determined the proportion and speed that would be required for identifying silent infections among this age group to suppress future attack rates below 5%.ResultsA targeted approach that identifies 20.6% and 28.6% of silent infections among children within 2 or 3 days post-infection, respectively, would be required to bring attack rates under 5% with vaccination of adults. If silent infections among children remained undetected, achieving the same attack rates would require an unrealistically high vaccination coverage (at least 82%) of this age group, in addition to the base-case 40% vaccination coverage of adults. The results were robust in sensitivity analyses with respect to vaccine efficacy against infection and reduced susceptibility of children to infection.Conclusions and RelevanceIn the absence of vaccine availability for children, a targeted approach to rapid identification of silent COVID-19 infections in this age group can significantly mitigate disease burden. Without measures to interrupt transmission chains from silent infections, vaccination of adults is unlikely to contain the outbreaks in the near term.Key PointsQuestionWhat is the impact of a targeted strategy for identification of silent COVID-19 infections among children in the absence of their vaccination?FindingsIn this modelling study, we found that identifying 20-30% of silent infections among children within three days post-infection would bring attack rates below 5% if only adults were vaccinated. If silent infections among children remained undetected, achieving the same attack rate would require an unrealistically high vaccination coverage (at least 82%) of this age group, in addition to vaccination of adults.MeaningRapid identification of silent infections among children can replicate effects of their vaccination.

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The impact of vaccination on COVID-19 outbreaks in the United States

Cited by 202 publications

References 40 publications

Optimizing vaccine allocation for COVID-19 vaccines: potential role of single-dose vaccination

Optimizing vaccine allocation for COVID-19 vaccines: potential role of single-dose vaccination

First indication of the effect of COVID-19 vaccinations on the course of the outbreak in Israel

Simulated identification of silent COVID-19 infections among children and estimated future infection rates with vaccination

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