To The Editor:
The messenger RNA vaccine BNT162b2 (Pfizer–BioNTech) has 95% efficacy towards coronavirus illness 2019 (Covid-19).1 Qatar launched a mass immunization marketing campaign with this vaccine on December 21, 2020. As of March 31, 2021, a complete of 385,853 individuals had acquired not less than one vaccine dose and 265,410 had accomplished the 2 doses. Vaccination scale-up occurred as Qatar was present process its second and third waves of extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) an infection, which have been triggered by growth of the B.1.1.7 variant (beginning in mid-January 2021) and the B.1.351 variant (beginning in mid-February 2021). The B.1.1.7 wave peaked through the first week of March, and the speedy growth of B.1.351 began in mid-March and continues to the current day. Viral genome sequencing performed from February 23 by March 18 indicated that fifty.0% of circumstances of Covid-19 in Qatar have been attributable to B.1.351 and 44.5% have been attributable to B.1.1.7. Practically all circumstances through which virus was sequenced after March 7 have been attributable to both B.1.351 or B.1.1.7.
Information on vaccinations, polymerase-chain-reaction testing, and medical traits have been extracted from the nationwide, federated Covid-19 databases which have captured all SARS-CoV-2–associated knowledge because the begin of the epidemic (Part S1 of the Supplementary Appendix, accessible with the total textual content of this letter at NEJM.org). Vaccine effectiveness was estimated with a test-negative case–management research design, a most well-liked design for assessing vaccine effectiveness towards influenza (see the Supplementary Appendix).2 A key energy of this design is the flexibility to manage for bias that will consequence from variations in well being care–looking for conduct between vaccinated and unvaccinated individuals.2
The estimated effectiveness of the vaccine towards any documented an infection with the B.1.1.7 variant was 89.5% (95% confidence interval [CI], 85.9 to 92.3) at 14 or extra days after the second dose (Desk 1 and Desk S2). The effectiveness towards any documented an infection with the B.1.351 variant was 75.0% (95% CI, 70.5 to 78.9). Vaccine effectiveness towards extreme, essential, or deadly illness resulting from an infection with any SARS-CoV-2 (with the B.1.1.7 and B.1.351 variants being predominant inside Qatar) was very excessive, at 97.4% (95% CI, 92.2 to 99.5). Sensitivity analyses confirmed these outcomes (Desk S3).
Vaccine effectiveness was additionally assessed with the usage of a cohort research design by evaluating the incidence of an infection amongst vaccinated individuals with the incidence within the nationwide cohort of individuals who have been antibody-negative (Part S2). Effectiveness was estimated to be 87.0% (95% CI, 81.8 to 90.7) towards the B.1.1.7 variant and 72.1% (95% CI, 66.4 to 76.8) towards the B.1.351 variant, findings that affirm the outcomes reported above.
The BNT162b2 vaccine was efficient towards an infection and illness within the inhabitants of Qatar, regardless of the B.1.1.7 and B.1.351 variants being predominant inside the nation; nevertheless, vaccine effectiveness towards the B.1.351 variant was roughly 20 share factors decrease than the effectiveness (>90%) reported within the medical trial1 and in real-world situations in Israel4 and the US.5 In Qatar, as of March 31, breakthrough infections have been recorded in 6689 individuals who had acquired one dose of the vaccine and in 1616 individuals who had acquired two doses. Seven deaths from Covid-19 have been additionally recorded amongst vaccinated individuals: 5 after the primary dose and two after the second dose. However, the diminished safety towards an infection with the B.1.351 variant didn’t appear to translate into poor safety towards essentially the most extreme types of an infection (i.e., these leading to hospitalization or dying), which was strong, at larger than 90%.
Laith J. Abu-Raddad, Ph.D.
Hiam Chemaitelly, M.Sc.
Weill Cornell Medication–Qatar, Doha, Qatar
Adeel A. Butt, M.D.
Hamad Medical Company, Doha, Qatar
for the Nationwide Research Group for COVID-19 Vaccination
Supported by the
Disclosure types offered by the authors can be found with the total textual content of this letter at NEJM.org.
This letter was printed on Could 5, 2021, at NEJM.org.
Members of the Nationwide Research Group for COVID-19 Vaccination are listed within the Supplementary Appendix, accessible with the total textual content of this letter at NEJM.org.
1. Polack FP, Thomas SJ, Kitchin N, et al. Security and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med 2020;383:2603–2615.
2. Jackson ML, Nelson JC. The test-negative design for estimating influenza vaccine effectiveness. Vaccine 2013;31:2165–2168.
3. COVID-19 medical administration: residing steering. Geneva: World Well being Group, January 25, 2021 (https://www.who.int/publications/i/merchandise/WHO-2019-nCoV-clinical-2021-1).
4. Dagan N, Barda N, Kepten E, et al. BNT162b2 mRNA Covid-19 vaccine in a nationwide mass vaccination setting. N Engl J Med 2021;384:1412–1423.
5. Thompson MG, Burgess JL, Naleway AL, et al. Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in stopping SARS-CoV-2 an infection amongst well being care personnel, first responders, and different important and frontline employees — eight U.S. areas, December 2020–March 2021. MMWR Morb Mortal Wkly Rep 2021;70:495–500.
|Kind of An infection or Illness||PCR-Optimistic Individuals||PCR-Detrimental Individuals||Effectiveness (95% CI)*|
|variety of individuals||%|
|PCR-confirmed an infection with the B.1.1.7 variant†|
|After one dose||892||18,075||1241||17,726||29.5 (22.9–35.5)|
|≥14 days after second dose||50||16,354||465||15,939||89.5 (85.9–92.3)|
|PCR-confirmed an infection with the B.1.351 variant‡|
|After one dose||1329||20,177||1580||19,926||16.9 (10.4–23.0)|
|≥14 days after second dose||179||19,396||698||18,877||75.0 (70.5–78.9)|
|Extreme, essential, or deadly illness attributable to the B.1.1.7 variant|
|After one dose||30||468||61||437||54.1 (26.1–71.9)|
|≥14 days after second dose||0||401||20||381||100.0 (81.7–100.0)|
|Extreme, essential, or deadly illness attributable to the B.1.351 variant|
|After one dose||45||348||35||358||0.0 (0.0–19.0)|
|≥14 days after second dose||0||300||14||286||100.0 (73.7–100.0)|
|Extreme, essential, or deadly illness attributable to any SARS-CoV-2|
|After one dose||139||1,966||220||1,885||39.4 (24.0–51.8)|
|≥14 days after second dose||3||1,692||109||1,586||97.4 (92.2–99.5)|