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(CNN) – Pfizer and BioNTech announced Tuesday that they have begun a clinical trial for a specific vaccine against the omicron variant of the coronavirus. And Moderna revealed Wednesday that it has entered phase 2 of its own study also for a specific vaccine against that variation of the virus, which is by far the dominant one in the United States right now.
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About 50% of eligible Americans have received a booster shot, according to the US Centers for Disease Control and Prevention (CDC). But the news about Pfizer and Moderna could raise questions anyway. Those who have not yet been vaccinated, should they wait until there is a specific vaccine against omicron? What if someone already had covid-19 during the omicron surge, do they still need a booster dose? And what does this mean for people who have already received a booster? Or for those who received the one-dose Johnson & Johnson vaccine and then received a different dose?
For the answers to these and other questions, I spoke with CNN Medical Analyst Dr. Leana Wen. Wen is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also the author of “Lifelines: A Doctor’s Journey in the Fight for Public Health.”
Should people wait until there is an omicron-specific vaccine for their booster dose?
Dr. Leana Wen: No, they shouldn’t. Everyone eligible for a booster should get it now.
Here are two key reasons for that. First, there is mounting evidence that a third dose from Pfizer or Moderna or a second vaccine after Johnson & Johnson is needed to maintain strong protection against covid-19. Last week, three large new studies from the CDC found that boosters protect against serious illness and reduce the likelihood of catching coronavirus.
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During a period in December and January, when omicron was dominant, one investigation found that receiving a booster dose was 90% effective in preventing hospitalization, compared to 57% effective seen in vaccinated people who did not have the third dose and whose second dose was more than six months ago. Another study looking at more than 13,000 cases of omicron found that participants with three doses were 66% less likely to develop a symptomatic infection compared to those with two.
Second, specific vaccines against omicron are still in clinical trials. The studies will take months to complete. We do not yet know the results of the trial and whether these variant-specific vaccines will be better than the original vaccines. Even if they do end up authorizing them, they are still months from now, and with omicron cases on the rise, people shouldn’t delay their booster shots.
If you’re an adult and it’s been at least five months after your second dose of Pfizer or Moderna, or two months after your only dose of Johnson & Johnson, you should get a booster. It is also recommended that adolescents 12 years of age and older get a third dose of the Pfizer vaccine if it has been at least five months since the second dose (only the Pfizer/BioNtech vaccine is licensed for adolescents 12 through 17 years of age).
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If someone gets their traditional booster now, does that mean they won’t be able to get the omicron-specific vaccine later?
No. One of the groups Pfizer is studying includes people who received three doses and are now receiving a fourth dose of the omicron-specific vaccine. The company will study the effect of this fourth dose. A fourth injection may not be needed because the initial booster continues to provide very good protection. But if the variant-specific booster, in addition to the third dose, is something that adds much more protection, the recommendation may well be that people get it in the future.
What if someone has just been infected with omicron? Should they still go for their regular booster now?
Most people don’t know which variant of covid-19 they had when they got it. But, since omicron now makes up more than 99% of new infections, if they recently contracted coronavirus it was probably omicron.
People who are vaccinated and have also recovered from the infection appear to have a very high degree of immune protection. However, the immunity of recovery is variable. Someone who has become seriously ill may have a stronger antibody response compared to someone who had an asymptomatic infection, and we don’t know how long that immunity lasts.
This is why boosters are still recommended for people who have had covid-19. They can get a booster as soon as their isolation period is over, as long as they no longer have a fever and their symptoms are improving.
The fourth dose of the vaccine raises antibodies, researchers say, but probably not enough to prevent post-vaccination omicron infections.
How long does the booster dose last? Do you think we’ll need another booster shot soon?
We do not know. A new preliminary study from the University of Texas, online but not yet peer-reviewed, found that antibodies against omicron remain strong four months after the booster dose. There are also other components of the immune response, T cells and B cells, that can remain strong for months. But we don’t yet know when immunity may wane after three injections. This is something the researchers will be watching very carefully. Meanwhile, the evidence is very clear that people need to get that booster dose.
What about people who initially got the Johnson & Johnson vaccine and then got their booster? Do they need a third dose?
I am one of these people. I initially received the one-dose Johnson & Johnson vaccine in a clinical trial and then decided to “mix and match” and got a booster from Pfizer.
I don’t think those of us who have received a second dose of any of the vaccines (Pfizer, Moderna, or J&J) after the initial J&J dose need to receive a third dose at this time. A study from South Africa found that a second dose of J&J was 85% effective against hospitalization during a period when omicron was circulating, compared to 63% after one dose. Another real patient study from the UK looked at the AstraZeneca vaccine, which is similar to J&J.
It found that while two doses of AstraZeneca provided little protection against omicron, a Pfizer booster after AstraZeneca resulted in 71% protection against symptomatic disease. This was a similar level of protection to those who received three doses of the Pfizer vaccine.
At the moment, the recommendation is that Americans who initially receive J&J are fine with a second dose of any of the three licensed vaccines. I do not plan to receive a third dose of vaccine any time soon. However, I think there has been a sense that federal health guidance has been delayed for J&J beneficiaries. And I hope there will be no delay in letting us know if the investigation reveals that a third dose is needed.
The fourth dose of the vaccine raises antibodies, researchers say, but probably not enough to prevent post-vaccination omicron infections.
Do you think that the development of omicron-specific vaccines will help speed up the end of the pandemic?
I am optimistic, in general, about the end of the covid-19 pandemic. It’s not that covid-19 is going to go away, it’s something that will surely be with us for the foreseeable future, but we have many more tools that will allow us to co-exist with the virus so that it doesn’t take over our lives.
Developing new vaccines will be a key part of living with covid-19. I hope there will be more vaccine research broadly targeting coronaviruses, so that if new mutations emerge, we don’t need to keep playing catch-up.
That said, I think it’s a good thing that companies are developing variant-specific vaccines, especially if they end up providing better and stronger protection. Again, though, we won’t know if that’s the case for months, and people really shouldn’t wait to get their boosters now.
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