1 Why is the vaccine manufactured by Novavax considered safer than those based on mRna?
Nuvaxovid, developed by the American biotech company, exploits the technique of recombinant proteins, well known and used for decades to produce vaccines (also administered to infants) such as those against hepatitis B, meningococcus B and Hpv. Compared to mRna vaccines, which instruct our cells to produce the coronavirus Spike protein, Nuvaxovid introduces the Spike protein directly into the body, developed in the laboratory in a mammalian cell line. Using vaccines based on recombinant proteins only activates the immune response, skipping the production phase of the Spike protein by our cells. The idea that this older generation method is safer because it does not use the wrong genetic material – says Sergio Abrignani, full professor of General Pathology and Immunology at the State University of Milan and director of the Romeo and Enrica Invernizzi Institute -. Indeed, we have definitive evidence that mRna vaccines are extremely safe and effective. If the Novavax vaccine can help overcome the doubts of some hesitant people, so be it.
2 What do we know about its effectiveness?
Two phase 3 studies were done. In the first, conducted in the UK on 14,000 people aged 18 and over, the vaccine achieved an overall effectiveness of 90 percent after two doses, against symptomatic Covid. This figure was confirmed in the second trial, which enrolled 30,000 participants in the United States and Mexico. The schedule includes two doses 21 days apart and the vaccine stored at 2-8 degrees. Studies are ongoing to evaluate efficacy after the third dose.
3 Can we hope that Nuvaxovid will defend against the Omicron variant?
We know that the protection remains good with the Alfa and Delta variants – underlines Abrignani -. As for Omicron we have to wait for the data on the third dose, but it is reasonable to expect a level of efficacy equal to that obtained with the mRna vaccines, which express the same Spike, that of the original Wuhan strain. Therefore an excellent efficacy, higher than 80%, against serious illness and a good protection against infection.
4 Will the protein vaccine be used for the booster?
Presumably s. A study recently published in the Lancet journal compared the effectiveness of seven vaccines in the third dose after Pfizer or AstraZeneca: Novavax was shown to be safe and effective as a booster. We know that the heterologous vaccination against Covid is more effective than the homologous one – clarifies Sergio Abrignani -. In addition, in clinical studies, Nuvaxovid induced a more robust immune reaction than mRna vaccines, at the level of neutralizing antibodies, already with two doses. A clarification must be made on this. The immune response consists of three elements: neutralizing antibodies (produced by B lymphocytes) and T lymphocytes, which are divided into CD4 and CD8. CD4s, called helpers, are the key cells for triggering the immune response. CD8s are the killers, meaning they kill cells infected with the virus. While mRna vaccines induce the production of all three components described, the protein vaccine only develops neutralizing antibodies and CD4 lymphocytes, not CD8. Since the efficacy of the protein vaccine is similar to that of mRna vaccines it can be concluded that the coverage of Covid vaccines does not require the production of CD8. it is sufficient for these lymphocytes to be activated when the infection occurs.
5 Will we need an updated vaccine for Omicron?
At the moment we are not certain on this point, but companies are already working on new versions of their preparations. A couple of weeks, as demonstrated by Moderna with the Beta variant, are enough to develop a new mRna vaccine. For the production and availability of the vaccine, as stated by Pfizer, it could take up to one hundred days – concludes Abrignani -. As for that of Novavax based on recombinant proteins, the times could be a little longer, I think it would take about 6 months to have the new formulation ready.
6 Will the protein vaccine also be used in children and adolescents?
So far, clinical studies have been conducted only on adults, but it is reasonable to think that in the next few months Novavax will also conduct trials in the lower age groups, as happened for messenger RNA-based vaccines.
December 21, 2021 (change December 21, 2021 | 10:02 am)
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