This week the European drug agency EMA and the Italian AIFA approved the fifth vaccine against Sars-CoV2: Nuvaxovid produced by the American Novavax.
What makes it different from currently approved vaccines and how could it help us fight the virus?
How Nuvaxovid works
Nuvaxovid is a vaccine that uses recombinant protein technology with the addition of an adjuvant. But let’s try to understand exactly how it works.
We have learned that vaccines work by ‘showing’ a virus or parts of it to our immune system, which will activate itself against them.
In the vaccine, therefore, a characteristic part of the virus is presented so that our immune system, ‘seeing it’, can attack it. For Covid19 in most cases it has been chosen to use the Spike protein that Sars-CoV2 uses as a ‘lock pick’ to open our cell doors.
Nuvaxovid is composed of the spike protein and a substance that stimulates the immune system called adjuvant.
The difference with mRNA vaccines is obvious where instead of immediately providing the spike we make our body produce it, in the case of Nuvaxovid we save our cells from fatigue and we supply it directly to them. Recombinant protein technology has been used for years in other vaccines such as that of hepatitis B or tetanus.
Effective and safe
In order for EMA and AIFA to approve the vaccine, the safety and production standards must be very high and also must prove to be at least as effective as those approved. Clinical trials of Nuvaxovid show efficacy in reducing symptomatic cases by approximately 90% and although we currently have no efficacy data on the Omicron variant we can expect similar efficacy to that seen in mRNA vaccines when given as a booster.
Let us remember that against the Omicron variant the greatest protection is given by 3 independent doses (also considering natural infection as one dose).
The Nuvaxovid protein vaccine similar to mRNA vaccines not only stimulates the production of neutralizing antibodies against Spike, but also stimulates T and B lymphocytes which play a vital role in fighting infection and severe disease.
How will it be used?
AIFA for the moment recommends its use to non-vaccinated subjects and therefore in a single cycle of two doses 3 weeks apart.
It is reasonable to expect Nuvaxovid to be used as a booster in Europe in the future as most of the population is already vaccinated against Covid19. Preliminary data show excellent results when Nuvaxovid is used in combination with mRNA or viral vector vaccines. Furthermore, the technical characteristics of this vaccine make it very interesting for developing countries where it is difficult to maintain the cold chain.
Nuvaxovid is not the only protein vaccine
Novavax vaccine is not the only protein vaccine approved and used. For months now, the Soberana and Abdala vaccines have been used in Cuba, which share many characteristics with Nuvaxoid: they are protein and use a substance as an adjuvant. Soberana has been shown to be extremely effective in reducing symptomatic disease in Cuba with an efficacy of over 90% and is currently one of the most widely administered protein vaccines in the world even in children (from two years of age).
Finally, it is worth remembering that Soberana has been designed and built to be administered in 3 doses in order to maximize the innate and adaptive immune response. Technically, the Soberana protocol involves the first two doses of the Soberana2 conjugate vaccine and the third ‘boost’ dose with an RBD-dimer.
More news on the way
In addition to our arsenal of mRNA vaccines and now a protein one, EMA is evaluating other more ‘classic’ vaccine types such as Valneva’s VLA2001 and Sinovac’s Covid19 vaccine. Both of these vaccines are inactivated, which means that the virus is grown in the laboratory and subsequently inactivated by a chemical.
The presence of the whole virus has advantages as it shows more viral proteins to our immune system but at the same time the inactivation process could modify the proteins and make them less recognizable.
TAKE HOME MESSAGE:
1) EMA and AIFA have approved the Nuvaxovid protein vaccine which should be available in Europe in early 2022
2) The efficacy is very high and although there are no data on Omicron it is expected that when used as a booster it will provide similar protection to mRNA vaccines
3) Nuvaxovid is not the only approved protein vaccine in the world, in fact Cuba has been successfully using the Soberana and Abdala vaccines in pediatrics for months
4) EMA is also evaluating other vaccines with different and classic technologies in order to increasingly enrich our arsenal against Covid19
Article written with the help of Fabrizio Chiodo researcher at the CNR and collaborator with the Vaccini Finlay Cuba institute.
REF
https://www.nejm.org/doi/full/10.1056/NEJMoa2116185
https://www.thelancet.com/action/showPdf?pii=S0140-6736%2821%2902718-5
https://www.ema.europa.eu/en/documents/product-information/nuvaxovid-epar-product-information_en.pdf
https://www.nature.com/articles/d41586-021-03470-x?utm_medium=affiliate&utm_source=commission_junction&utm_campaign=3_nsn6445_deeplink_PID100384925&utm_content=deeplink
Aureliano Stingi, doctor in molecular biology works in the field of precision oncology. Collaborate with the World Health Organization in the battle against Covid19-themed fake news
Twitter: @AurelianoStingi
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