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1.
The Lancet Respiratory Medicine ; 2022.
Article in English | ScienceDirect | ID: covidwho-1799636

ABSTRACT

Summary Background The duration of protection against the omicron (B.1.1.529) variant for current COVID-19 vaccines is not well characterised. Vaccine-specific estimates are especially needed. We aimed to evaluate the effectiveness and durability of two and three doses of the BNT162b2 (Pfizer–BioNTech) mRNA vaccine against hospital and emergency department admissions due to the delta (B.1.617.2) and omicron variants. Methods In this case–control study with a test-negative design, we analysed electronic health records of members of Kaiser Permanente Southern California (KPSC), a large integrated health system in California, USA, from Dec 1, 2021, to Feb 6, 2022. Vaccine effectiveness was calculated in KPSC patients aged 18 years and older admitted to hospital or an emergency department (without a subsequent hospital admission) with a diagnosis of acute respiratory infection and tested for SARS-CoV-2 via PCR. Adjusted vaccine effectiveness was estimated with odds ratios from adjusted logistic regression models. This study is registered with ClinicalTrials.gov (NCT04848584). Findings Analyses were done for 11 123 hospital or emergency department admissions. In adjusted analyses, effectiveness of two doses of the BNT162b2 vaccine against the omicron variant was 41% (95% CI 21–55) against hospital admission and 31% (16–43) against emergency department admission at 9 months or longer after the second dose. After three doses, effectiveness of BNT162b2 against hospital admission due to the omicron variant was 85% (95% CI 80–89) at less than 3 months but fell to 55% (28–71) at 3 months or longer, although confidence intervals were wide for the latter estimate. Against emergency department admission, the effectiveness of three doses of BNT162b2 against the omicron variant was 77% (72–81) at less than 3 months but fell to 53% (36–66) at 3 months or longer. Trends in waning against SARS-CoV-2 outcomes due to the delta variant were generally similar, but with higher effectiveness estimates at each timepoint than those seen for the omicron variant. Interpretation Three doses of BNT162b2 conferred high protection against hospital and emergency department admission due to both the delta and omicron variants in the first 3 months after vaccination. However, 3 months after receipt of a third dose, waning was apparent against SARS-CoV-2 outcomes due to the omicron variant, including hospital admission. Additional doses of current, adapted, or novel COVD-19 vaccines might be needed to maintain high levels of protection against subsequent waves of SARS-CoV-2 caused by the omicron variant or future variants with similar escape potential. Funding Pfizer.

2.
Lancet Reg Health Am ; : 100198, 2022 Feb 14.
Article in English | MEDLINE | ID: covidwho-1693148

ABSTRACT

Background: Globally, recommendations are expanding for third (booster) doses of BNT162b2 (Pfizer-BioNTech). In the United States, as of November 19, 2021, boosters were recommended for all adults aged 18 years and older. We evaluated the effectiveness of a third dose of BNT162b2 among adults in a large US integrated health system. Methods: In this retrospective cohort study, we analyzed electronic health records from Kaiser Permanente Southern California between Dec 14, 2020 and Dec 5, 2021 to assess vaccine effectiveness (VE) of two and three doses of BNT162b2 against SARS-CoV-2 infections (without hospital admission) andCOVID-19-related hospital admission. VE was calculated using hazards ratios from adjusted Cox models. Findings: After only two doses, VE against infection declined from 85% (95% CI 83-86) during the first month to 49% (46-51) ≥ 7 months following vaccination. Overall VE against hospitalization was 90% (95% CI 86-92) within one month and did not wane, however, effectiveness against hospitalization appeared to wane among immunocompromised individuals but was not statistically significant (93% [72-98] at 1 month to 74% [45-88] after ≥ 7 months; p=0·490). Three-dose VE (median follow-up 1·3 months [SD 0·6]) was 88% (95% CI 86-89) against infection and 97% (95-98) against hospitalization. Effectiveness after three doses was higher than that seen one month after receiving only two doses for both outcomes. Relative VE of three doses compared to two (with at least six months after the second dose) was 75% (95% CI 71-78) against infections and 70% (48-83) against hospital admissions. Interpretation: These data support the benefit of broad BNT162b2 booster recommendations, as three doses confers comparable, if not better, protection against SARS-CoV-2 infections and hospital admission as was seen soon after receiving two doses. Funding: Pfizer Inc.

3.
Lancet Regional Health. Americas ; 2022.
Article in English | EuropePMC | ID: covidwho-1679198

ABSTRACT

Background Globally, recommendations are expanding for third (booster) doses of BNT162b2 (Pfizer–BioNTech). In the United States, as of November 19, 2021, boosters were recommended for all adults aged 18 years and older. We evaluated the effectiveness of a third dose of BNT162b2 among adults in a large US integrated health system. Methods In this retrospective cohort study, we analyzed electronic health records from Kaiser Permanente Southern California between Dec 14, 2020 and Dec 5, 2021 to assess vaccine effectiveness (VE) of two and three doses of BNT162b2 against SARS-CoV-2 infections (without hospital admission) andCOVID-19-related hospital admission. VE was calculated using hazards ratios from adjusted Cox models. Findings After only two doses, VE against infection declined from 85% (95% CI 83–86) during the first month to 49% (46–51) ≥ 7 months following vaccination. Overall VE against hospitalization was 90% (95% CI 86–92) within one month and did not wane, however, effectiveness against hospitalization appeared to wane among immunocompromised individuals but was not statistically significant (93% [72–98] at 1 month to 74% [45–88] after ≥ 7 months;p=0·490). Three-dose VE (median follow-up 1·3 months [SD 0·6]) was 88% (95% CI 86–89) against infection and 97% (95–98) against hospitalization. Effectiveness after three doses was higher than that seen one month after receiving only two doses for both outcomes. Relative VE of three doses compared to two (with at least six months after the second dose) was 75% (95% CI 71−78) against infections and 70% (48−83) against hospital admissions. Interpretation These data support the benefit of broad BNT162b2 booster recommendations, as three doses confers comparable, if not better, protection against SARS-CoV-2 infections and hospital admission as was seen soon after receiving two doses. Funding Pfizer Inc.

4.
Lancet ; 398(10309): 1407-1416, 2021 10 16.
Article in English | MEDLINE | ID: covidwho-1447246

ABSTRACT

BACKGROUND: Vaccine effectiveness studies have not differentiated the effect of the delta (B.1.617.2) variant and potential waning immunity in observed reductions in effectiveness against SARS-CoV-2 infections. We aimed to evaluate overall and variant-specific effectiveness of BNT162b2 (tozinameran, Pfizer-BioNTech) against SARS-CoV-2 infections and COVID-19-related hospital admissions by time since vaccination among members of a large US health-care system. METHODS: In this retrospective cohort study, we analysed electronic health records of individuals (≥12 years) who were members of the health-care organisation Kaiser Permanente Southern California (CA, USA), to assess BNT162b2 vaccine effectiveness against SARS-CoV-2 infections and COVID-19-related hospital admissions for up to 6 months. Participants were required to have 1 year or more previous membership of the organisation. Outcomes comprised SARS-CoV-2 PCR-positive tests and COVID-19-related hospital admissions. Effectiveness calculations were based on hazard ratios from adjusted Cox models. This study was registered with ClinicalTrials.gov, NCT04848584. FINDINGS: Between Dec 14, 2020, and Aug 8, 2021, of 4 920 549 individuals assessed for eligibility, we included 3 436 957 (median age 45 years [IQR 29-61]; 1 799 395 [52·4%] female and 1 637 394 [47·6%] male). For fully vaccinated individuals, effectiveness against SARS-CoV-2 infections was 73% (95% CI 72-74) and against COVID-19-related hospital admissions was 90% (89-92). Effectiveness against infections declined from 88% (95% CI 86-89) during the first month after full vaccination to 47% (43-51) after 5 months. Among sequenced infections, vaccine effectiveness against infections of the delta variant was high during the first month after full vaccination (93% [95% CI 85-97]) but declined to 53% [39-65] after 4 months. Effectiveness against other (non-delta) variants the first month after full vaccination was also high at 97% (95% CI 95-99), but waned to 67% (45-80) at 4-5 months. Vaccine effectiveness against hospital admissions for infections with the delta variant for all ages was high overall (93% [95% CI 84-96]) up to 6 months. INTERPRETATION: Our results provide support for high effectiveness of BNT162b2 against hospital admissions up until around 6 months after being fully vaccinated, even in the face of widespread dissemination of the delta variant. Reduction in vaccine effectiveness against SARS-CoV-2 infections over time is probably primarily due to waning immunity with time rather than the delta variant escaping vaccine protection. FUNDING: Pfizer.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , RNA, Messenger/immunology , SARS-CoV-2/immunology , Adolescent , Adult , Aged , Aged, 80 and over , Child , Delivery of Health Care, Integrated , Female , Hospitalization/statistics & numerical data , Humans , Male , Middle Aged , Organizations , Retrospective Studies , Time Factors , United States , Vaccination/statistics & numerical data
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