The Pfizer/BioNTech Covid-19 vaccine provides some protection against the new omicron variant, but people may need three injections instead of two to get the same level of protection, based on preliminary result From a laboratory test conducted by the company. The level of protection provided by a more comprehensive messenger RNA vaccine and whether a specific version of omicron is needed awaits more data from real-world research.
At a press conference on Wednesday, BioNTech CEO Ugur Sahin said that although the previous variant had 10 to 15 mutations, omicron had 34 to 35 mutations. Sahin says that many of these mutations occur in a part of the spike protein called the receptor binding domain-this part binds to a protein on the cell surface to enter the cell.
Some mutations of omicron are shared with other variants of the new coronavirus. This means that the current version of the Covid-19 vaccine is still effective, but preliminary data suggests that its effect has diminished. BioNTech has not yet released data for peer review. In preliminary laboratory data released on Wednesday, BioNTech stated that it tested people’s blood samples one month after receiving the booster-the third injection after the initial series of two vaccinations. According to the company, the average level of neutralizing antibodies against omicron has been reduced by more than 25 times, indicating that two doses may not provide adequate protection for the new variant.
In addition to prompting the immune system to produce neutralizing antibodies, the Covid-19 vaccine can also cause a T cell response. Memory T cells are especially important because these cells remain for a long time after infection and are ready to respond quickly when the pathogen returns. BioNTech Chief Medical Officer Ozlem Türeci said that the presence of these memory T cells may still prevent serious diseases caused by omicron variants. BioNTech expects two doses to provide protection against serious diseases, however, a third dose may be required to obtain the protection provided by the neutralizing antibody. Türeci added that these preliminary data “show us that the first line of defense of the two doses of vaccine may be compromised, and three doses of vaccine are needed to restore protection.”
Shahin said that a mutation evaluation study started nine months ago to prepare for potential changes in the vaccine. Clinical trials for beta, delta and alpha variants are ongoing. Another clinical trial is evaluating a vaccine that can prevent both alpha and delta variants. In tests against the beta variant, the level of neutralizing antibodies was reduced by a factor of five. Sahin said these results indicate that omicron is a stronger neutralizing antibody escape variant.
“It is still not a complete escape variant; it is a partial escape variant,” he said. “This means that the virus can be neutralized by a high-titer neutralizing antibody.”
According to the company, preliminary data suggests that current boosters of messenger RNA vaccines can increase antibody levels by 25 times. This additional injection will also increase the level of T cells that respond to multiple parts of the spike protein attached to the antibody to provide additional protection. According to the company, most of these components remain unchanged in the omicron variant.
Sahin said that BioNTech will continue to develop omicron-specific vaccines if needed. The need for such a vaccine will depend on data from real-world studies that show the speed of omicron’s spread and the effectiveness of current vaccines against new variants. Sahin said it may take six to eight weeks to obtain the data.
Omicron was first discovered in South Africa last monthThe omicron specific version of the Pfizer/BioNTech vaccine has been designed; Sahin said that if it turns out to be needed, the vaccine can be ready for delivery by March, waiting for regulatory approval. He added that the omicron variant vaccine should be a three-dose vaccine. The vaccine can also provide protection against more than one variant. Shahin pointed out that ongoing clinical trials of variants have shown that multivalent vaccines can be produced, but more data is needed to determine whether such changes are necessary.
Photo: Robin Baker/AFP, via Getty Images
