AstraZeneca, Pfizer, Moderna, J&J: differences between the efficacy and side effects of COVID-19 vaccines

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SAN FRANCISCO – Another vaccine against COVID-19, AstraZeneca, is about to hit the United States, providing a fourth option for Americans. Each vaccine is given slightly differently, some may cause different side effects, and studies have shown variable efficacy. We are breaking down the key differences between the available COVID-19 vaccines, in addition to the likely approval of AstraZeneca.

What are the options?

Pfizer, Moderna, and Johnson & Johnson vaccines have already been authorized for emergency use by the FDA. AstraZeneca is expected to apply for emergency use authorization in the coming weeks.

Which vaccines require one dose and which require two doses?

Johnson & Johnson is the only single vaccine. The others require two doses at different time intervals. Pfizer suggests that the two doses be given three weeks apart, Moderna four weeks apart and AstraZeneca four or 12 weeks apart.

How effective are vaccines?

In a clinical trial, Pfizer claims that its vaccine was 95% effective in preventing cases of COVID-19 with symptoms and 100% effective in preventing severe cases. Modern cited similar results, with 94% effectiveness.

Johnson & Johnson found that their vaccine, which was tested in the U.S. amid a larger increase in COVID-19 transmission, was 72% effective overall and 86% effective in preventing serious illness.

The most recent U.S. trial showed that the AstraZeneca vaccine was 79% effective in preventing symptomatic cases of COVID-19 and was 100% effective in stopping severe cases and hospitalization.

Which vaccine is most effective?

A precaution before comparing the previous efficacy indices in parallel: clinical trials of the vaccine were performed under different conditions, which could give different results. For example, the Johnson & Johnson vaccine was tested in an environment with many more COVID-19 variants circulating and at a time when cases were increasing. The “best” vaccine is the one offered to you, doctors keep reminding the public.

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What are the side effects of each vaccine?

The three approved vaccines have the same common side effects, according to the disease control centers:

  • Pain, redness and / or swelling in the arm where the shot is fired
  • Tired
  • Headache
  • Shivers
  • Fever
  • Nausea

Concern about blood clots caused several European countries to stop using the AstraZeneca vaccine. However, the European Medicines Agency has concluded, following an investigation, that the vaccine did not increase the overall risk of blood clots, but could not rule out that it was connected to two very rare types of clots.

In the latest trial conducted in the United States with 20,000 people, experts found no increased risk of blood clots.

Which vaccines are most common in the US?

According to the CDC, the U.S. has received about 77 million doses of Pfizer, 75 million doses of Modern and 4 million doses of J&J at the time of publication. Remember: the J&J vaccine only requires one dose, but two doses of Pfizer or Moderna are needed to completely vaccinate a person.

Can I choose which vaccine I get?

Right now, no. Possible options may fall on the line if supply grows enough.

The Associated Press contributed to this report.

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