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Covid-19 variant first found in Brazil is up to 2.2 times more transmissible, new study finds

There are now three Covid-19 vaccines approved for emergency use by the United States Food and Drug Administration, manufactured by Pfizer / BioNTech, Moderna, and Johnson & Johnson. All three will be distributed in the United States.

Many people wonder which Covid-19 vaccine they should get: is one better for certain groups of people? Given the number of people who still cannot get vaccinated, will people have a choice? If so, which vaccine should they choose?

We asked CNN medical analyst Dr. Leana Wen for her opinion. Wen is an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health.

Wen is also volunteering in the Johnson & Johnson clinical trial, although she is not yet sure whether she received the vaccine or a placebo.

Can you explain the differences between the three vaccines authorized by the FDA? What do we know about their safety and effectiveness?

Dr Leana Wen: The vaccines from Pfizer and Moderna were first authorized in December. They are similar to each other in that they are both developed using the mRNA platform. The Johnson & Johnson vaccine has just been authorized. He uses a different way of stimulating an immune response, with a cold virus inactivated. Both Pfizer and Moderna vaccines require two injections. Johnson & Johnson has just been licensed as a single dose vaccine.

All three vaccines have very favorable safety profiles, which means they are all very safe when tested in tens of thousands of people. All three are practically 100% in clinical trials for the prevention of hospitalizations and deaths, which is the criterion that is very close to our hearts.

The Pfizer and Moderna vaccines appear to be more effective at preventing mild to moderate illness, around 95%. The Johnson & Johnson vaccine is about 72% effective, according to US trials. However, these results should not be compared directly, as the trials were not performed as direct comparisons.

Why not? You can see why people would look at those numbers and say 95%. 100 versus 72 p. I’ll take the one that’s 95%.

Dr Leana Wen: This is an understandable concern. Here are three reasons why this isn’t the right comparison.

First, vaccines have been studied at different times. The Pfizer and Moderna studies were done before these more worrisome variants became a major factor.

Second, one of the main places where the Johnson & Johnson vaccine has been studied was South Africa, where the predominant variant at the time of the study was the B.1.351 variant. There is concern that none of the vaccines we have available will work as well against this variant.

For the Johnson & Johnson vaccine, it appears to be less effective against the South African variant as well. However, it is still very effective. Even in South Africa, the vaccine prevented 82% of serious illnesses (compared to 86% in the United States).

Third, remember that the Johnson & Johnson vaccine is a single dose vaccine. This greatly simplifies the logistics so that you do not have to make a second appointment and assign second doses.

Read more answers about Dr Wen’s vaccines here:


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