U.S. Department of Health & Human Services

09/17/2021 | Press release | Distributed by Public on 09/18/2021 21:15

COVID-19 Science Update released: September 17, 2021 Edition 105


Note: Adapted from Naaber et al. Antibody responses S-RBD IgG in individuals vaccinated with BNT162b2 (Comirnaty, Pfizer/BioNTech), before vaccination (B1D, n = 88), after 1 dose (B2D, n = 111), 1 week after 2 doses (1wA2D, n = 106);6 weeks after 2 doses(6wA2D, n = 89); 12 weeks after 2 doses (12wA2D, n = 90);6 months after 2 doses(6mA2D; n = 84); compared with post-infection levels in patients recovered from COVID-19 (COVID-19, n = 97); and pre-COVID-19 negative controls (NC, n = 50). Licensed under CC-BY-NC-ND.

  • Effectiveness of the BNT162b2 mRNA COVID-19 vaccine in pregnancyexternal icon . Dagan et al. Nature Medicine (September 7, 2021). Among 21,722 (half vaccinated, half matched controls) pregnant women in Israel, BNT162b2 (Comirnaty, Pfizer/BioNTech) vaccine effectiveness was 96% (95% CI 89%-100%) for all infections up to 56 days after 2nd dose, 97% (95% CI 91%-100%) for symptomatic infections and 89% (95% CI 43%-100%) for hospitalization. Results reflect effectiveness mainly against original SARS-CoV-2 and Alpha (B.1.1.7), the dominant strains during the study period.

Note: Adapted from Dagan et al. Cumulative incidence of SARS-CoV-2 infection by time among vaccinated and unvaccinated pregnant women, December 20, 2020-June 3, 2021. Permission request in process.

Note: Adapted from Bahl et al. Trends (crude and estimated rates) in weekly emergency department (ED) encounters of COVID-19 patients by vaccination status. The point at which a line changes to a different color indicates the week that a significant change in trend occurred. Permission request in process.


Natural History, Reinfection, and Health Impact

  • COVID-19 mortality in children and young people in Mexicoexternal icon . Stern et al. medRxiv (Preprint; September 5, 2021). In 2020, COVID-19 accounted for 4.4% (95% CI 4.1%-4.6%) of deaths in children ages 0-9 years and 3.7% (95% CI 3.4%-4.1%) in adolescents ages 10-19 years in Mexico. From January 2020 to July 2021, the largest increase in cumulative COVID-19 mortality was among children <1 year and adolescents 15-19 years.

Note: Adapted from Stern et al. Mortality trends of children and adolescents in Mexico January 1, 2020-July 10, 2021 A) <1 year>B) children and adolescents aged 1-19 years. Arrows indicate date of peak all-age reported mortality per day from COVID-19. Numbers above arrows correspond to the cumulative mortality/100,000 adults on the dates of peak (July 2020 and January 2021). Used by permission of authors.

  • Hospitalisation among vaccine breakthrough COVID-19 infectionsexternal icon . Juthani et al. The Lancet Infectious Diseases (September 7, 2021). Among 969 patients hospitalized with confirmed SARS-CoV-2, 14/54 (26%) of fully vaccinated patients were severely or critically ill (median age 80·5 years); 3 died. Among those with severe/critical disease, pre-existing comorbidities were overweight (n = 9), cardiovascular disease (n = 12), lung disease (n = 7), malignancy (n = 4), type 2 diabetes (n = 7), immunosuppressants (n = 4). 13/14 patients had been vaccinated with BNT162b2 (Comirnaty, Pfizer/BioNTech) at least 14 days before symptom onset or a positive SARS-CoV-2 test.

Note: Adapted from Juthani et al.A) Classification of all patients admitted to a Connecticut hospital March 23, 2021-July 1, 2021 with positive SARS-CoV-2 PCR test by vaccination status. B) Disease severity among fully vaccinated, hospitalized patients with positive SARS-CoV-2 PCR test. C) Disease severity among fully vaccinated individuals by vaccine type. Severe/critical disease includes respiratory failure, septic shock, and/or multiple organ dysfunction. Reprinted from The Lancet Infectious Diseases, September 7, 2021, Juthani et al., Hospitalisation among vaccine breakthrough COVID-19 infections, online ahead of print. Copyright 2021, with permission from Elsevier.

Prevention Strategies and Non-Pharmaceutical Interventions

Note: Adapted from Love et al. Heatmaps of the impact of vaccine coverage on COVID-19 deaths. Warmer colors indicate more deaths/infections. Licensed under CC BY.


  • SARS-CoV-2 testing prior to international airline travel, December 2020-May 2021external icon . Tande et al. Mayo Clinic Proceedings (September 2, 2021). Among 9,853 passengers with a negative SARS-CoV-2 PCR test conducted ≤ 72 hours of departure, 5 passengers (0.05%) were identified as SARS-CoV-2 positive from rapid antigen tests and confirmed with rapid molecular tests performed both before and after commercial flights from the US to Italy between December 2020 and May 2021. This translates to a low case detection rate of 1/1970 travelers during a time of high SARS-CoV-2 infection rates in the US.

Note: Adapted from Tande et al. SARS-CoV-2 testing algorithm used for commercial flights from the United States to Italy, December 2020-May 2021. Licensed under CC BY 4.0.

Transmission Risk and Dynamics

Note: Adapted from Somekh et al. Weekly adjusted incidence (new SARS-CoV-2 cases/100,000 in children aged 0-9 years). Linear regression curves are the lines connecting the dots. Dates represent day 1 of the study week. Licensed under CC BY.

Health Equity

  • COVID-19 vaccine efficacy in a diverse urban healthcare worker populationexternal icon . Iliaki et al. medRxiv (Preprint; September 6, 2021). Among 4,317 Massachusetts healthcare workers (HCWs), 3,249 were vaccinated between December 2020 and March 2021 and vaccine effectiveness was 95.5% (95% CI 88.2%-98.3%) for those fully vaccinated. Vaccinated HCWs were older, more likely to be non-Hispanic White persons, and to be medical providers. Vaccine uptake among African-American HCWs was lower (54%) than among White HCWs (83%).

From the Morbidity and Mortality Weekly Report (September 17, 2021).