Short Term Reduction in the Odds of Testing Positive for SARS-CoV-2; a Comparison Between Two Doses and Three doses of the BNT162b2 Vaccine

With the evidence of waning immunity of the BNT162b2 vaccine, a national third dose vaccination campaign was initiated in Israel during August 2021; other countries have announced their intention to administer a booster shot as well. Leveraging data from Maccabi Healthcare Services, we conducted a preliminary retrospective study aimed at evaluating initial short-term effectiveness of a three dose versus a two dose regimen against infection due to the Delta variant of SARS-CoV-2, using two complementary approaches; a test-negative design and a matched case-control design. We found that 7-13 days after the booster shot there is a 48-68% reduction in the odds of testing positive for SARS-CoV-2 infection and that 14-20 days after the booster the marginal effectiveness increases to 70-84%. Further studies are needed to determine the duration of protection conferred by the third dose and its effect on severe disease.

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Waning Effectiveness of the BNT162b2 Vaccine Against Infection in Adolescents

10.1101/2022.01.04.22268776 ◽

2022 ◽

Author(s):

Ottavia Prunas ◽

Daniel M. Weinberger ◽

Virginia E. Pitzer ◽

Sivan Gazit ◽

Tal Patalon

Keyword(s):

Control Design ◽

Healthcare Services ◽

Case Control ◽

Vaccine Effectiveness ◽

Age Group ◽

Short Term ◽

Symptomatic Infection ◽

Matched Case ◽

Induced Immunity

Background: The short-term effectiveness of a two-dose regimen of the BioNTech/Pfizer mRNA BNT162b2 vaccine for adolescents has been demonstrated. However, little is known about the long-term effectiveness in this age group. It is known, though, that waning of vaccine-induced immunity against infection in adult populations is evident within a few months. Methods: Leveraging the centralized computerized database of Maccabi Healthcare Services (MHS), we conducted a matched case-control design for evaluating the association between time since vaccination and the incidence of infections, where two outcomes were evaluated separately: a documented SARS-CoV-2 infection (regardless of symptoms) and a symptomatic infection (COVID-19). Cases were defined as individuals aged 12 to 16 with a positive PCR test occurring between June 15 and December 8, 2021, when the Delta variant was dominant in Israel. Controls were adolescents who had not tested positive previously. Results: We estimated a peak vaccine effectiveness between 2 weeks and 3 months following receipt of the second dose, with 85% and 90% effectiveness against SARS-CoV-2 infection and COVID-19, respectively. However, in line with previous findings for adults, waning of vaccine effectiveness was evident in adolescents as well. Long-term protection conferred by the vaccine was reduced to 75-78% against infection and symptomatic infection, respectively, 3 to 5 months after the second dose, and waned to 58% against infection and 65% against COVID-19 after 5 months. Conclusions: Like adults, vaccine-induced protection against both SARS-CoV-2 infection and COVID-19 wanes with time, starting three months after inoculation and continuing for more than five months.

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Correlation of SARS-CoV-2 Breakthrough Infections to Time-from-vaccine; Preliminary Study

10.1101/2021.07.29.21261317 ◽

2021 ◽

Author(s):

Roni Lotan ◽

Sivan Gazit ◽

Gabriel Chodik ◽

Tal Patalon ◽

Galit Perez ◽

...

Keyword(s):

Clinical Trials ◽

Vaccination Campaign ◽

Preliminary Finding ◽

Healthcare Services ◽

Breakthrough Infection ◽

Short Term ◽

Booster Vaccine ◽

Preliminary Study ◽

Different Strains

The short-term effectiveness of a two-dose regimen of the BioNTech/Pfizer mRNA BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine was widely demonstrated. However, long term effectiveness is still unknown. A nationwide vaccination campaign was initiated early in Israel, allowing for a real-world evaluation of the interaction between protection and time-from-vaccine. The Delta (B.1.617.2) variant became the dominant strain in Israel in June 2021, as Israel is currently experiencing a new surge of cases. Leveraging the centralized computerized database of Maccabi Healthcare Services (MHS), we assessed the correlation between time-from-vaccine and incidence of breakthrough infection. We found that the risk for infection was significantly higher for early vaccinees compared to those vaccinated later. This preliminary finding should prompt further investigagions into long-term protection against different strains, and prospective clinical trials to examine the effect of a booster vaccine against breakthrough infection.

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Alternative observational designs to estimate the effectiveness of one dose of oral cholera vaccine in Lusaka, Zambia

Epidemiology and Infection ◽

10.1017/s095026882000062x ◽

2020 ◽

Vol 148 ◽

Author(s):

E. Ferreras ◽

A. Blake ◽

O. Chewe ◽

J. Mwaba ◽

G. Zulu ◽

...

Keyword(s):

Cohort Study ◽

Vaccination Campaign ◽

Case Control ◽

Cholera Vaccine ◽

Mass Vaccination Campaign ◽

Negative Case ◽

Oral Cholera Vaccine ◽

Matched Case ◽

Polymerase Chain ◽

Study Designs

Abstract We conducted a matched case-control (MCC), test-negative case-control (TNCC) and case-cohort study in 2016 in Lusaka, Zambia, following a mass vaccination campaign. Confirmed cholera cases served as cases in all three study designs. In the TNCC, control-subjects were cases with negative cholera culture and polymerase chain reaction results. Matched controls by age and sex were selected among neighbours of the confirmed cases in the MCC study. For the case-cohort study, we recruited a cohort of randomly selected individuals living in areas considered at-risk of cholera. We recruited 211 suspected cases (66 confirmed cholera cases and 145 non-cholera diarrhoea cases), 1055 matched controls and a cohort of 921. Adjusted vaccine effectiveness of one dose of oral cholera vaccine (OCV) was 88.9% (95% confidence interval (CI) 42.7–97.8) in the MCC study, 80.2% (95% CI: 16.9–95.3) in the TNCC design and 89.4% (95% CI: 64.6–96.9) in the case-cohort study. Three study designs confirmed the short-term effectiveness of single dose OCV. Major healthcare-seeking behaviour bias did not appear to affect our estimates. Most of the protection among vaccinated individuals could be attributed to the direct effect of the vaccine.

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