This vaccine is the first vaccine approved in Europe or the U.S. that is based on a protein, a technology used in many other vaccines, such as influenza.

This vaccine consists of protein S in its prefused form and with the furin cleavage site removed, which is expressed in insect cells, purified and mixed with an adjuvant to boost the immune response.

In the case of the other covid-19 vaccines that are approved in Europe or the U.S. the adjuvant is not necessary because either the messenger RNA envelope (Pfizer or Moderna) or the viral vector (AstraZeneca or Janssen) performs the function of the adjuvant.

The Novavax vaccine is delivered in two intramuscular doses of 5 µg protein S + 50 µg adjuvant.

The vaccine has been tested in several clinical trials in the UK, USA and Mexico, in total comparing more than 24,000 vaccinees with more than 15,000 placebo recipients.

The clinical trials have involved people aged 18 to 64 years and over 65 years. In the U.S.-Mexico trial they found 63 symptomatic infections in the placebo group versus 14 in the vaccinated group. And in the UK trial they found 96 symptomatic patients in the placebo group and 10 in the vaccinated group. Therefore, the efficacy of the vaccine has been estimated at around 90 % in preventing symptomatic infection, and higher in preventing severe disease.

In summary, this vaccine is based on a technology long known in the field of vaccines, is safe and effective in preventing symptoms caused by the variants circulating at the time of the trial (mainly alpha and beta). An advantage of this vaccine is that it does not require ultracold, so it could be more easily distributed to parts of the world where other vaccines are difficult to reach.

This vaccine uses only the protein of the spicule (S), with an adjuvant substance to enhance the response. The technology is partly novel, in the cell type that produces the proteins, in nanoparticulated form, and also in the type of adjuvant used. But recombinant proteins are already used in other vaccines, such as hepatitis B, with great success.

It is a vaccine that has been shown to be very effective against SARS-CoV-2, with 90 % protection against infection with symptoms in clinical trials (when mainly the alpha and beta variants were circulating), and its effect on the omicron variant is not yet known. It has been shown in trials (more than 45,000 recruited persons over 18 years of age) to be very safe, and with very few side effects (arm pain, tiredness, headache and nausea).

The company's proprietary adjuvant, Matrix-M, helps to elicit a potent antibody and T-cell response. It has already been tested in other vaccines, such as a vaccine under study for malaria. An advantage over mRNA vaccines is that it does not require deep-freezing. It can be kept in the refrigerator (between 2 and 8°C), which makes it an excellent vaccine forcountries where the logistics of other vaccines are a problem.

Its efficacy against omicron has yet to be demonstrated, bu it is expected that vaccinated persons will continue to respond to this variant, although its recognition may decrease somewhat.

It is important to point out that this vaccine cannot replicate, does not produce disease and does not integrate.

The vaccine is for intramuscular injection and in two doses 21 days apart, although surely if this period were extended, the immune response generated could be even greater, according to the data obtained with other vaccines.

In summary, we have a new vaccine that can be used, very safely, with high efficacy and with advantages in terms of logistics because it does not require deep freezing. Moreover, the production of the protein will be carried out in a Spanish company, Biofabri, in Porriño, near Vigo, which is very good news.

It is very good news to have a new vaccine that has been evaluated by independent expert committees from international organizations, which really do an in-depth study on safety and efficacy. This vaccine uses a technology that is already known and has worked very well in other vaccines. It offers the advantage that it does not need to be kept in such extreme cold conditions as RNA vaccines, which simplifies transport and maintenance.