Efficacy of Pfizer-BioNTech’s BNT162b2 vaccine against teenage SARS-CoV-2 delta and omicron variants

In a recent study posted on medRxiv* Preprint server, researchers administered two and three doses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant (VOC) such as Delta and adolescent community residents in Canada. Later Pfizer-BioNTech’s BNT162b2 vaccine was evaluated for efficacy (VE).

Background

BNT162b2 vaccination, approved for use in adolescents 16 years and older, was expanded to Canada and the United States (US) in May 2021 to include 12 to 15 years old.Double BNT162b2 vaccination showed> 90% Effectiveness Phase III study for SARS-CoV-2 infection in adolescents from the second vaccination to 4 months.

To this end, the National Advisory Board on Immunity (NACI) advises to increase the interval between first and second vaccinations in British Columbia (BC) and Quebec, Canada, from March 2021. did. In addition, three BNT162b2 vaccinations for adolescent individuals began in February 2022 in two Canadian states.

About research

In this study, researchers evaluated double and triple BNT162b2 messenger ribonucleic acid (mRNA) VE for omicrons and deltas in adolescents living in British Columbia and Quebec, Canada. (TND).

BNT162b2VE was rated against Nucleic acid Amplification test (NAAT)-Confirmed 2019 coronavirus infection (COVID-19) in teenagers (cases) aged 12 to 17 years from September 5, 2021 to April 30, 2022. NAAT-negative adolescents (controls) were analyzed for comparison. The period of Delta dominance was considered to be from September 5, 2021 to November 27, and the period of Omicron dominance was considered to be from December 19, 2021 to April 30, 2022.

Vaccination details were provided by the COVID-19 Surveillance Registry in two Canadian states. VE was assessed for 2 weeks by the dosing interval between the two vaccinations and the time elapsed after the second and third vaccinations. Logistic regression modeling was used to estimate adjusted odds ratios (AORs) for COVID-19 in 2- and 3-fold BNT162b2 vaccinated adolescents compared to unvaccinated adolescents.

Covariates such as age, gender, region, and calendar time. The region includes 18 geographical regions of Quebec, 5 sites (Greater Quebec City, Greater Montreal, Northern Quebec, Central Quebec, and other regions) and 5 BC regions (Inside, Fraser, Vancouver Island, Grouped in the north (and the coast of Vancouver). ..

result

In British Columbia and Quebec, the team sampled 60,903 and 193,899 adolescents, of which 11% (n = 6,673) and 11% (n = 20,570) included 0.9% (n = 59), respectively. It was NAAT positive. 0.8% (n = 159) of hospitalized adolescents, respectively. Positive rates were lower in vaccinated adolescents than in unvaccinated adolescents, and no deaths were observed among study participants. Most cases in Quebec (63%) and BC (68%) occurred 20 weeks after the second vaccination, during the period in which Omicron was predominant.

The interval between the first and second doses was 8 weeks, and the interval between the second and third doses was 28-31 weeks. The average follow-up period after the second vaccination during the Delta and Omicron predominant period was 10-11 weeks and 21-22 weeks, respectively, and the average follow-up period after the third vaccination was 3-9 weeks. ..

During the transition period (Delta to Omicron), VE was slightly lower at 83% in Quebec and 88% in BC. During the period when Omicron was dominant, VE was further reduced to 42% and 34%, respectively. In Quebec, adjusted double-dose VE was slightly higher than symptomatic COVID-19 in the delta-dominant (97%), delta-omicron transition period (88%), and omicron-dominant period (55%). rice field.

VE for delta VOCs was more than 90% up to 5 months after the second vaccination. In contrast, VE for Omicron VOCs decreased from 65% to 75% within 2-3 weeks after vaccination, to less than 50% within 3 months after vaccination, and for a short period after the third vaccination. It returned from 60% to 65%. Over 90% of VE was observed for Delta regardless of dosing interval, but improved for Omicron at intervals of 8 weeks or more between the first and second vaccinations.

VE estimates differed slightly in Quebec with respect to limiting analysis to symptomatic adolescents only, reflecting the symptom-based SARS-CoV-2 test in the Canadian province (≤10% higher). ). In both states, the SARS-CoV-2 testing policy was changed in mid-January to target people at high risk of serious COVID-19 results that may have affected VE estimates for Omicron. ..

Vaccine cards or passports are mandatory to participate in entertainment or social settings in both states from September 2021 and were lifted in mid-March (Quebec) or early April (BC). This may increase the risk of exposure to vaccinated adolescents. -VE estimation. However, VE remained high until November and Delta’s predominance.

Conclusion

Overall, study results showed that two BNT162b2 vaccinations provided strong, long-term immune defense against delta VOCs, but diminished with the rapid decline of VE against omicron VOCs, among adolescents. .. However, increasing the dosing interval between vaccinations and the third vaccination increased protection against Omicron. Therefore, increasing dosing intervals and doses may improve adolescent VE for antigenic SARS-CoV-2VOC.

Further studies in randomized controlled trials are needed to assess the effects of confounding variables associated with SARS-CoV-2 infection and vaccination probabilities. Future studies will need to stratify data by comorbidities such as immunodeficiency, taking into account the size of the household, the presence of young siblings (not eligible for vaccination), and socioeconomic conditions.

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.