Pfizer vaccine 'extraordinarily effective' against UK and SA variants — Two studies

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The Pfizer-BioNTech coronavirus vaccine is "extraordinarily effective" at protecting against severe disease caused by two dangerous variants, according to two studies, reports The New York Times.

The studies, which are based on the real-world use of the vaccine in Qatar and Israel, suggest that the vaccine can prevent the worst outcomes — including severe pneumonia and death — caused by B.1.1.7, the variant first identified in the UK, and B.1.351, the variant first identified in South Africa.

“This is really good news,” said Dr Annelies Wilder-Smith, an infectious disease researcher at the London School of Hygiene and Tropical Medicine. “At this point in time, we can confidently say that we can use this vaccine, even in the presence of circulating variants of concern.”

Previous research suggested that B.1.1.7 is more infectious and more deadly than other variants but that vaccines still worked well against it. On the other hand, vaccines appeared to be less effective against B.1.351, according to earlier studies.

One of the new studies, which appeared in the New England Journal of Medicine, is based on information about more than 200,000 people that was pulled from Qatar’s national Covid-19 databases between Feb. 1 and March 31.

In multiple analyses, the researchers found that the vaccine was 87 to 89.5 percent effective at preventing infection with B.1.1.7 among people who were at least two weeks past their second shot. It was 72.1 to 75 percent effective at preventing infection with B.1.351 among those who had reached the two-week point.

The vaccine was highly effective at protecting against the worst outcomes. Overall, it was 97.4 percent effective at preventing severe, critical or fatal disease from any form of the coronavirus, and 100 percent effective at preventing severe, critical or fatal disease caused by B.1.1.7 or B.1.351.

The second new study, which was published in The Lancet, was conducted by researchers at Pfizer and at Israel’s Ministry of Health. It is based on more than 230,000 instances of coronavirus infection that occurred in Israel between Jan. 24 and April 3. During that period, B.1.1.7 accounted for nearly 95 percent of all coronavirus cases in the country, which has vaccinated more than half of its population.

The researchers found that the vaccine was more than 95 percent effective at protecting against coronavirus infection, hospitalization and death among fully vaccinated people 16 and older. It also worked well in older adults. Among those 85 or older, the vaccine was more than 94 percent effective at preventing infection, hospitalisation and death.

 

New England Journal of Medicine study

Effectiveness of the BNT162b2 Covid-19 Vaccine against the B.1.1.7 and B.1.351 Variants

Authors: Laith J Abu-Raddad, Hiam Chemaitelly, Adeel A Butt

Published in The New England Journal of Medicine on 5 May 2021

The messenger RNA vaccine BNT162b2 (Pfizer–BioNTech) has 95% efficacy against coronavirus disease 2019 (Covid-19).1 Qatar launched a mass immunization campaign with this vaccine on December 21, 2020. As of March 31, 2021, a total of 385,853 persons had received at least one vaccine dose and 265,410 had completed the two doses. Vaccination scale-up occurred as Qatar was undergoing its second and third waves of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which were triggered by expansion of the B.1.1.7 variant (starting in mid-January 2021) and the B.1.351 variant (starting in mid-February 2021). The B.1.1.7 wave peaked during the first week of March, and the rapid expansion of B.1.351 started in mid-March and continues to the present day. Viral genome sequencing conducted from February 23 through March 18 indicated that 50.0% of cases of Covid-19 in Qatar were caused by B.1.351 and 44.5% were caused by B.1.1.7. Nearly all cases in which virus was sequenced after March 7 were caused by either B.1.351 or B.1.1.7.

Data on vaccinations, polymerase-chain-reaction testing, and clinical characteristics were extracted from the national, federated Covid-19 databases that have captured all SARS-CoV-2–related data since the start of the epidemic (Section S1 of the Supplementary Appendix, available with the full text of this letter at NEJM.org). Vaccine effectiveness was estimated with a test-negative case–control study design, a preferred design for assessing vaccine effectiveness against influenza. A key strength of this design is the ability to control for bias that may result from differences in health care–seeking behavior between vaccinated and unvaccinated persons.

Vaccine Effectiveness against Infection and against Disease in Qatar

The estimated effectiveness of the vaccine against any documented infection with the B.1.1.7 variant was 89.5% (95% confidence interval [CI], 85.9 to 92.3) at 14 or more days after the second dose. The effectiveness against any documented infection with the B.1.351 variant was 75.0% (95% CI, 70.5 to 78.9). Vaccine effectiveness against severe, critical, or fatal disease due to infection with any SARS-CoV-2 (with the B.1.1.7 and B.1.351 variants being predominant within Qatar) was very high, at 97.4% (95% CI, 92.2 to 99.5). Sensitivity analyses confirmed these results.

Vaccine effectiveness was also assessed with the use of a cohort study design by comparing the incidence of infection among vaccinated persons with the incidence in the national cohort of persons who were antibody-negative. Effectiveness was estimated to be 87.0% (95% CI, 81.8 to 90.7) against the B.1.1.7 variant and 72.1% (95% CI, 66.4 to 76.8) against the B.1.351 variant, findings that confirm the results reported above.

The BNT162b2 vaccine was effective against infection and disease in the population of Qatar, despite the B.1.1.7 and B.1.351 variants being predominant within the country; however, vaccine effectiveness against the B.1.351 variant was approximately 20 percentage points lower than the effectiveness (>90%) reported in the clinical trial1 and in real-world conditions in Israel4 and the United States.5 In Qatar, as of March 31, breakthrough infections have been recorded in 6689 persons who had received one dose of the vaccine and in 1616 persons who had received two doses. Seven deaths from Covid-19 have been also recorded among vaccinated persons: five after the first dose and two after the second dose. Nevertheless, the reduced protection against infection with the B.1.351 variant did not seem to translate into poor protection against the most severe forms of infection (i.e., those resulting in hospitalization or death), which was robust, at greater than 90%.

 

The Lancet study details

Impact and effectiveness of mRNA BNT162b2 vaccine against SARS-CoV-2 infections and COVID-19 cases, hospitalisations, and deaths following a nationwide vaccination campaign in Israel: an observational study using national surveillance data

Authors: Eric J Haas, Frederick J Angulo, John M McLaughlin, Emilia Anis, Shepherd R Singer, Farid Khan, et al.

Published 8 May 2021 in The Lancet

Summary

Background

Following the emergency use authorisation of the Pfizer–BioNTech mRNA COVID-19 vaccine BNT162b2 (international non-proprietary name tozinameran) in Israel, the Ministry of Health (MoH) launched a campaign to immunise the 6·5 million residents of Israel aged 16 years and older. We estimated the real-world effectiveness of two doses of BNT162b2 against a range of SARS-CoV-2 outcomes and to evaluate the nationwide public-health impact following the widespread introduction of the vaccine.
Methods

We used national surveillance data from the first 4 months of the nationwide vaccination campaign to ascertain incident cases of laboratory-confirmed SARS-CoV-2 infections and outcomes, as well as vaccine uptake in residents of Israel aged 16 years and older. Vaccine effectiveness against SARS-CoV-2 outcomes (asymptomatic infection, symptomatic infection, and COVID-19-related hospitalisation, severe or critical hospitalisation, and death) was calculated on the basis of incidence rates in fully vaccinated individuals (defined as those for whom 7 days had passed since receiving the second dose of vaccine) compared with rates in unvaccinated individuals (who had not received any doses of the vaccine), with use of a negative binomial regression model adjusted for age group (16–24, 25–34, 35–44, 45–54, 55–64, 65–74, 75–84, and ≥85 years), sex, and calendar week. The proportion of spike gene target failures on PCR test among a nationwide convenience-sample of SARS-CoV-2-positive specimens was used to estimate the prevelance of the B.1.1.7 variant.
Findings

During the analysis period (Jan 24 to April 3, 2021), there were 232 268 SARS-CoV-2 infections, 7694 COVID-19 hospitalisations, 4481 severe or critical COVID-19 hospitalisations, and 1113 COVID-19 deaths in people aged 16 years or older. By April 3, 2021, 4 714 932 (72·1%) of 6 538 911 people aged 16 years and older were fully vaccinated with two doses of BNT162b2. Adjusted estimates of vaccine effectiveness at 7 days or longer after the second dose were 95·3% (95% CI 94·9–95·7; incidence rate 91·5 per 100 000 person-days in unvaccinated vs 3·1 per 100 000 person-days in fully vaccinated individuals) against SARS-CoV-2 infection, 91·5% (90·7–92·2; 40·9 vs 1·8 per 100 000 person-days) against asymptomatic SARS-CoV-2 infection, 97·0% (96·7–97·2; 32·5 vs 0·8 per 100 000 person-days) against symptomatic COVID-19, 97·2% (96·8–97·5; 4·6 vs 0·3 per 100 000 person-days) against COVID-19-related hospitalisation, 97·5% (97·1–97·8; 2·7 vs 0·2 per 100 000 person-days) against severe or critical COVID-19-related hospitalisation, and 96·7% (96·0–97·3; 0·6 vs 0·1 per 100 000 person-days) against COVID-19-related death. In all age groups, as vaccine coverage increased, the incidence of SARS-CoV-2 outcomes declined. 8006 of 8472 samples tested showed a spike gene target failure, giving an estimated prevalence of the B.1.1.7 variant of 94·5% among SARS-CoV-2 infections.
Interpretation

Two doses of BNT162b2 are highly effective across all age groups (≥16 years, including older adults aged ≥85 years) in preventing symptomatic and asymptomatic SARS-CoV-2 infections and COVID-19-related hospitalisations, severe disease, and death, including those caused by the B.1.1.7 SARS-CoV-2 variant. There were marked and sustained declines in SARS-CoV-2 incidence corresponding to increasing vaccine coverage. These findings suggest that COVID-19 vaccination can help to control the pandemic.

 

Full New York Times report (Restricted access)

 

Full NEJM material (Open access)

 

Full The Lancet material (Open access)


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