What's the concern about the new COVID-19 variants? Are they more contagious?
Answer From Daniel C. DeSimone, M.D.
Viruses constantly change through mutation. When a virus has one or more new mutations it’s called a variant of the original virus. Currently, several variants of the virus (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) are creating concern in the U.S. These variants include:
- Delta (B.1.617.2). This variant is now the most common COVID-19 variant in the U.S. It potentially spreads more easily than other variants. Research has shown that it spreads easily in indoor sports settings and households. This variant also might reduce the effectiveness of some monoclonal antibody treatments and the antibodies generated by a COVID-19 vaccine.
- Alpha. (B.1.1.7). This COVID-19 variant appears to spread more easily, with about a 50% increase in transmission compared to previous circulating variants. This variant also might have an increased risk of hospitalization and death.
- Gamma (P.1). This variant reduces the effectiveness of some monoclonal antibody medications and the antibodies generated by a previous COVID-19 infection or a COVID-19 vaccine.
- Beta (B.1.351). This variant appears to spread more easily, with about a 50% increase in transmission compared to previous circulating variants. It also reduces the effectiveness of some monoclonal antibody medications and the antibodies generated by a previous COVID-19 infection or COVID-19 vaccine.
While research suggests that COVID-19 vaccines are slightly less effective against the variants, the vaccines still appear to provide protection against severe COVID-19. For example:
- Early research from the U.K. suggests that, after full vaccination, the Pfizer-BioNTech COVID-19 vaccine is 88% effective at preventing symptomatic COVID-19 virus caused by the delta variant. The vaccine is 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant. The research also showed that the vaccine is 93% effective at preventing symptomatic COVID-19 virus caused by the alpha variant.
- Early research from Canada suggests that, after one dose, the Moderna COVID-19 vaccine is 72% effective at preventing symptomatic COVID-19 virus caused by the delta variant. One dose of the vaccine is also 96% effective at preventing severe disease with the COVID-19 virus caused by the delta variant.
- The Janssen/Johnson & Johnson COVID-19 vaccine is 85% effective at preventing severe disease with the COVID-19 virus caused by the delta variant, according to data released by Johnson & Johnson.
In addition, vaccine manufacturers are also creating booster shots to improve protection against variants.
Keep in mind, if you are fully vaccinated, the overall risk of hospitalization and death due to COVID-19 is much lower than among unvaccinated people with similar risk factors.
With
Daniel C. DeSimone, M.D.
July 15, 2021
- Dougherty K, et al. SARS-CoV-2 B.1.617.2 (Delta) variant COVID-19 outbreak associated with a gymnastics facility — Oklahoma, April-May 2021. MMWR Morbidity Mortality Weekly Report. 2021. doi:10.15585/mmwr.mm7028e2.
- Lopez Bernal J, et al. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. medRxiv. In press. doi:10.1101/2021.05.22.21257658.
- Stowe J, et al. Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant. In press. Accessed July 13, 2021.
- Emerging SARS-CoV-2 variant VUI 202012/01. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-emerging-variant.html. Accessed Jan. 29, 2021.
- COVID data tracker: Variant proportions. Centers for Disease Control and Prevention. https://covid.cdc.gov/covid-data-tracker/#variant-proportions. Accessed July 13, 2021.
- About variants of the virus that causes COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/variants/variant.html. Accessed July 13, 2021.
- The effects of virus variants on COVID-19 vaccines. World Health Organization. https://www.who.int/news-room/feature-stories/detail/the-effects-of-virus-variants-on-covid-19-vaccines. Accessed June 16, 2021.
- Positive new data for Johnson & Johnson single-shot COVID-19 vaccine on activity against delta variant and long-lasting durability of response. Johnson & Johnson. https://www.jnj.com/positive-new-data-for-johnson-johnson-single-shot-covid-19-vaccine-on-activity-against-delta-variant-and-long-lasting-durability-of-response. Accessed July 13, 2021.
- What you should know about the possibility of COVID-19 illness after vaccination. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/effectiveness/why-measure-effectiveness/breakthrough-cases.html. Accessed July 13, 2021.
- Mahase E. Covid-19: What new variants are emerging and how are they being investigated? BMJ. 2021; doi:10.1136/bmj.n158.
- Wu K, et al. mRNA-1273 vaccine induce neutralizing antibodies against spike mutants from global SARS-Cov-2 variants. bioRxiv. In press. doi:10.1101/2021.01.25.427948.
- Moderna COVID-19 vaccine retains neutralizing activity against emerging variants first identified in the U.K. and the Republic of South Africa. Moderna, Inc. https://investors.modernatx.com/news-releases/news-release-details/moderna-covid-19-vaccine-retains-neutralizing-activity-against. Accessed Jan. 29, 2021.
- Wang Z, et al. mRNA vaccine-elicited antibodies to SARS-CoV-2 and circulating variants. bioRxiv. 2021; doi: 10.1101/2021.01.15.426911.
- SARS-CoV-2 variants. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant-info.html#Concern. Accessed March 18, 2021.
- Nasreen S, et al. Effectiveness of COVID-19 vaccines against variants of concern, Canada. medRxiv. 2021; doi:10.1101/2021.06.28.2125942.
- SARS-CoV-2 variant classifications and definitions. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html. Accessed July 13, 2021.