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By now, you may have heard about COVID-19 variants that emerged in the fall and winter of 2020.
Variants are changes on viral proteins due to mutations (which are random genetic changes that occur during viral replication). Most mutations are inconsequential, but viral evolution can occur when there is a high rate of transmission and viral replication.
Let’s look at the common cold, for example. Common cold coronavirus 229E infects the average person every 2-3 years. After infection with a 229E, antibodies are produced against targets on the spike protein. Mutations that change the targets on the spike protein make the antibodies less able to neutralize the virus (or reduce its ability to replicate). A library of 229E viruses dating back to 1979 shows that mutations on the spike protein are responsible for the common cold’s evolution and its ability to cause repeated infections.
SARS-CoV-2, unlike the common cold coronavirus 229E, can cause severe pneumonia, respiratory failure and death. While the global spread of SARS-CoV-2 has been rapid, it has been stalled through mitigation efforts: stay-at-home orders, masking, physical distancing, hygiene and finally, vaccination.
What do we know about the mutations that have occurred in SARS-CoV-2?
This demonstrates how the coronavirus can evolve under selection pressures, when there is ongoing transmission, and replication.
What do we know about effectiveness of COVID-19 vaccines against SARS-CoV-2 variants?
The two COVID-19 mRNA vaccines, Pfizer BNT162B2 and Moderna MRNA-1273, FDA-approved under Emergency Use Authorization (EUA), showed 94-95% efficacy in protection against symptomatic COVID-19 and near complete protection against severe infection.
Sera from patients who participated in the phase 1 clinical trials and completed two doses of Moderna vaccine was tested against the B.1.1.7 (UK) and B.1.351 (South Africa) variants. There was no significant reduction in the neutralization against the B.1.1.7 variant, meaning the vaccine was still protective. While there was a six-fold reduction in activity against the B.1.351 variant, it was still above the level to be protective.
In contrast, plasma from patients who recovered from natural infection with COVID-19 did not neutralize the B.1.351 (South African) variant. This is consistent with the studies that show antibody levels from mRNA vaccines to be greater than the upper half of levels found in convalescent plasma.
What about the other COVID-19 vaccines being planned?
Another two-dose vaccine on the horizon, Novavax COVID-19 (a protein conjugate vaccine), showed nearly equivalent preliminary efficacy against the B.1.1.7 (UK) variant (86%) as the non-B.1.1.7 variant (96%). It was 60% efficacious for the South African variant.
Johnson and Johnson announced results of the phase 3 trial for its single dose Janssen COVID-19 vaccine. It was 72% efficacious in the U.S., 66% in Latin America and 57% in South Africa (where 90% of infections were due to the B.1.351 variant). It was 85% efficacious against severe infection in all groups and there were no hospitalizations in any of the vaccine participants.
Vaccines can be updated with boosters that cover newer variants. Moderna is working on a booster that covers the B.1.351 (South Africa) variant. MRNA vaccines provide excellent protection against the circulating strains of SARS-CoV-2 in the United States. The vaccines protect just as well against B.1.1.7 (UK) variant, but also provide protection against the more resistant B.1.351 (South Africa) variant. All of the vaccines likely protect against severe infection from variant strains.
What’s the takeaway?
COVID-19 infection can lead to temporary immunity, but also allows for more transmission, and an opportunity for the virus to mutate and evolve, leading to variant strains and a resurgence of reinfections. In contrast, COVID-19 vaccinations produce an immune response that is greater than natural infection. The vaccines prevent symptomatic and severe infection, decrease transmission and decrease the chances for viral evolution.
COVID-19 cases are finally decreasing because of all that you are doing to prevent transmission. Wearing masks, physically distancing at least 6 feet, avoiding social gatherings and getting the COVID-19 vaccine as soon as it is offered to you will also prevent the spread of variant SARS-CoV-2. There is hope for a time when enough of the population is immunized to get to herd immunity and make COVID-19 a rarity.
Are you wondering whether to get the vaccine? Read our blog to learn more.
Edward-Elmhurst Health also offers screening options for COVID-19. Eleanor, your personal virtual assistant, can help you check your symptoms 24/7 and advise you on what to do next. We also offer Video Visits and E-Visits for COVID-19 symptoms.
For COVID-19 updates, please check EEHealth.org/coronavirus.
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