Tech & Innovation in Healthcare

Answer: When the COVID-19 vaccines were initially developed, the messenger ribonucleic acid (mRNA) formula aimed to target the original strain of the virus. However, the SARS-CoV-2 virus has been constantly changing since it emerged. This moving target makes it difficult for vaccine manufacturers to combat the variants before the variants can affect the public.

The new formulations of the COVID-19 vaccine made by Moderna and Pfizer-BioNTech are bivalent vaccines, and they contain two parts of mRNA that target the original COVID-19 strain plus the BA.4 and BA.5 subvariants. Once administered, the vaccines instruct the body’s cells to construct the spike proteins of all three components, so your body will know to fight the original virus and the two subvariants.

The spike proteins of BA.4 and BA.5 are similar, which is why so many variations of the protein can avoid the vaccinated or previously infected patient’s antibodies and cause an infection.

According to the Centers for Disease Control and Prevention (CDC) NOWCAST for the week ending Sept. 24, 2022, COVID-19 subvariants accounted for the following percentages of the total cases in the U.S.:

• BA.5: 83.1 percent
• BA.4: 1.4 percent

BA.4.6 is a new subvariant and this strain accounted for 11.9 percent of all U.S. COVID-19 cases.

On Aug. 31, 2022, the U.S. Food and Drug Administration (FDA) amended the emergency use authorizations (EUAs) for the Pfizer-BioNTech and Moderna COVID-19 vaccines “to authorize bivalent formulations of the vaccines for use as a single booster dose at least two months following primary or booster vaccination.”