February brought us exciting news about vaccines as well as troubling news about COVID-19 variants. There has been confusion about how these variants may impact vaccine effectiveness. Hopefully this blog post helps clear up some of that confusion.
New Variants
In the last couple of months, new variants (strains or mutations) of COVID have been found across the globe. Virus mutations are common and expected, but mutations are concerning as scientists are still learning about COVID-19. Dr. Klase, an associate professor of pharmacology at Drexel University College of Medicine, explains why virus mutations are common: Every time a virus penetrates a human cell, it must make copies of itself and its genetic code. About two to three mistakes (mutations) happen each time a virus copies itself. Some mistakes make it more difficult for the virus to spread, some make it easier for the virus to spread, but most have no impact at all. The versions that make the virus easier to transmit will naturally prevail (as cited in Avril, 2021).
Currently, we have learned of variants circulating in the U.S. that were initially discovered in the U.K., South Africa, and Brazil. We are also discovering mutations that appear to have originated here in the U.S. According to the CDC (2021), at this time, there is no evidence that the variants lead to an increase in severity of illness; however, this is being studied. The variants discovered in the U.K., South Africa, and Brazil appear to be more contagious than other strains.
At the time of writing this post, the most concerning variant in the United States is the B.1.1.7 U.K. Cavender (2021) of the Lehigh Valley Health Network explains the strain is “probably more widespread than we realize” because the common COVID tests do not test for the strain. Instead, the strain was detected in U.S. COVID cases via random tests done by the CDC to sequence the virus and detect mutations. That genetic testing is not yet widespread, so it is possible the variant is more common than we currently realize.
Rettner (2021) tells readers the variant detected in South Africa, B.1.351, has eight spike protein mutations. This variant has been detected in more than 30 countries and is the dominant strain in South Africa. This variant appears to share some of the same mutations as the U.K. variant.
P.1, the Brazilian variant, is especially concerning because it quickly became the dominant strain in the Brazilian city of Manaus. Also, similar to the South Africa strain, it carries a “cluster” of mutations (Doucleff (2021.
CDC guidance for preventing the spread of COVID has not changed with the new variants. We must continue to be vigilant and wear masks, wash our hands, and practice social distancing.
New Vaccines
Johnson & Johnson
At the end of February, 2021, the U.S. FDA granted emergency use authorization (EUA) to Johson & Johnson’s coronavirus vaccine (FDA, 2021). Its effectiveness against moderate COVID infection ranged depending on the country, variant, and trial participants; however it was at least 66% effective overall. In terms of preventing severe infection, it was 85% effective across all participants (Fox, Sealy, & Nedelman, 2021). It is also 100% effective against infection that is so severe it leads to hospitalization and death (Johnson and McGinley, 2021).
The Johnson & Johnson vaccine is a single dose vaccine whereas the Pfizer and Moderna brands are double dose vaccines. Also, unlike the Pfizer and Moderna vaccines, the Johnson & Johnson vaccine is an adenovirus vaccine rather than an mRNA vaccine. For information about how mRNA vaccines work, check out my Common COVID-19 Vaccine Questions blog post.
An adenovirus vaccine uses a weakened virus to help the body build an immune response. According to the CDC (2019), an adenovirus is a common virus that causes a range of infections, from the common cold to pink eye. Shipman (2020) explains how the adenovirus vaccines, which have been around for some time but have not yet been approved for use, work: genes for the protein we want the immune system to fight (in this case, the SARS-CoV-2 spike protein) are injected into the adenovirus as DNA. The person is injected with the adenovirus, and when the adenovirus gets to your cells, the injected DNA is converted into mRNA for your body. The mRNA instructs your immune system to create a defense against the protein. The adenovirus vaccines contain the instructions to fight COVID, not the virus itself. Mahalingam and Taylor (2020) tell us there are pros and cons to adenovirus vaccines. They often stimulate long-term protection after just one dose; however, people may already have protection to the virus vector which would reduce the effectiveness of the vaccine. Mahalingam and Taylor (2020)’s article is a great resource to quickly learn about various types of vaccines on the market today and how they work.
Vaccines on the Horizon
Oxford AztraZeneca created an adenovirus vaccine for COVID. It has been approved for EUA in the U.K. and E.U. but not in the U.S. Bruek (2021) tells readers this vaccine will likely not be available in the U.S. before spring because of odd and serious errors in its European trials. It is currently conducting a phase III trial in the U.S. with 30,000 people.
Novavax Inc. has also created a COVID-19 vaccine, and it is currently doing phase III clinical trials of its vaccine in the U.S. According to Annett and Langreth (2021), the company will likely obtain EUA in the U.K. before the U.S., but the U.S. FDA could approve it for EUA here if clinical trials abroad yield positive results.
Vaccines vs. Variants
Companies report varying levels of effectiveness for their vaccines against different variants, but it’s critical to note that even if the vaccines are “less effective” against certain strains, they are still highly effective. Joseph (2021) tells readers the reason vaccines currently approved and those in development will still work against the variants is because the vaccines produce “a polyclonal response, generating numerous antibodies that home in on different parts of the virus. Changes to any of those target sites raise the possibility that the vaccines would be less effective, not that they won’t work at all” (para. 3).
Although the vaccines are still effective, manufacturers are working on ways to modify their vaccines in the future to stay ahead of the variants; in fact, Moderna is currently working on ways to modify its vaccine or offer a booster in the future (Johsnon, McGinley, Achenbach, 2021). Pfizer also recently began trials with a third booster shot (Pfizer, 2021).
University of Cambridge virus expert Ravi Gupta says scientists are in a game of “cat and mouse” with the virus, and it’s likely they will need to adjust the vaccines each year for new variants just like scientists must do with flu vaccines (as cited in Doucleff, 2021).
There is hope that adjusting the vaccines for COVID-19 variants will be easier than adjusting the flu vaccines. According to Avril (2021), the flu virus is “segmented,” meaning that it can mutate a few letters of its genetic code at any time just like any virus, but it can also swap out entire segments of its genetic code. Each year, scientists are making their best guess about what parts of the code will mutate and swap, and they adjust vaccines accordingly. The COVD-19 virus is not segmented, so scientists only have to worry about mutations to the code; COVID-19 will not swap entire segments of its code. So far, the mutations that have occurred represent only a small fraction of the entire 30,000 letter genetic code (“Why the Vaccines Are Still Good,” paras. 2-3).
The bottom line is, scientists recommend getting your vaccine (unless contraindicated due to health concerns) as soon as you’re able to regardless of which type it is because they are all effective in fighting the variants.
Christina J. Steffy 