In February 2021, the only Covid-19 vaccines available in the United States are the very similar mRNA-based vaccines from Pfizer and Moderna, both of which were reported to be 94-95% effective at preventing symptomatic Covid-19 in study participants who got the vaccine. A “real world” test, following the results of vaccinated people in Israel, has reassured us that the trial results were valid. Among 600,000 people who got the Pfizer vaccine, there was a 94% drop in symptomatic cases, only 4 severe cases and no deaths.
The problems with these vaccines are that there is simply not an adequate supply to vaccinate everyone in the U.S. soon enough, and that the price, need for two shots and the logistics of storing and transporting the vaccines limit how widely they can be used. Given the interconnectedness of the modern world, mass vaccination of the entire planet will be needed before any of us are truly safe. Happily, many other vaccines are well along in development.
A vaccine from Johnson and Johnson is closest to getting emergency use authorization in the U.S. This vaccine uses an adenovirus, a generally harmless virus, modified to carry the gene for the Coronavirus “spike protein” into human cells, which then produce this protein, which induces our immune system to recognize and fight off Covid-19 if we are exposed to it. This vaccine has many desirable qualities: it only requires one shot and it can be stored for months at normal refrigerator temperatures, making it much easier to distribute and administer.
You may have seen headlines indicating that it was only 66% effective at preventing symptomatic Covid-19, well below the efficacy of the mRNA vaccines. To some degree this is not a fair “apples to apples” comparison. The J&J vaccine was tested later than the mRNA vaccines, and it was tested in South America, Mexico and South Africa as well as in the U.S., while the Moderna vaccine was only tested in the U.S. The J&J shot thus had to contend with the new strains of virus, and we now know that the mRNA vaccines are less effective against these new strains than the original Coronavirus. Importantly, the J&J vaccine was 85% effective at preventing severe Covid-19, and there were no deaths in the vaccinated group.
Another candidate on the near horizon is from U.S. biotech firm Novavax. This vaccine combines a protein mimicking the virus’ spike protein with a “adjuvant,” a non-specific immune system stimulator. Preliminary trial results have shown 95% efficacy against the original SARS-CoV-2 virus and 86% against the B.1.1.7 (British) and 60% against the B.1.351 (South African) variants. Trials have been done in Great Britain and South Africa, and the vaccine requires two shots, 3 weeks apart, and can be stored at normal refrigerator temperature.
The Russian “Sputnik V” is another two-shot adenovirus-based vaccine. While the Russians were criticized for rolling out the vaccine before testing was complete, the preliminary trials have shown a 92% efficacy at preventing symptomatic Covid-19. Efficacy was similar across all age groups, and there were no severe cases in people who received both shots.
The Oxford/Astra Zeneca vaccine uses a modified adenovirus with DNA coding for the spike protein to generate an immune response. It got a lot of bad press when preliminary results showed better protection in those who had mistakenly gotten a lower dose than planned for their first dose followed by the planned second dose. This did not make biologic sense and put the trial into question. The larger trial has now shown 76% efficacy after one dose and 82% after a second. There were no Covid-19 hospitalizations in the vaccinated group. The vaccine has been approved for use in the United Kingdom.
Which vaccine should you get? To answer that question requires you to grasp one crucial fact: there have been essentially NO DEATHS from Covid-19 in people who got any of the available or soon to be available vaccines. We are not going to “wipe out” Covid-19. There have been and will continue to be coronaviruses circulating among us. What we need to get life back to normal is to eliminate deaths and markedly reduce hospitalizations from the SARS-CoV-2 virus. If Covid-19 can become just another cold that we catch and get over, we can go back to eating out, attending concerts and hugging each other.
So: take which ever vaccine you are offered!
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