Antibody levels fell to low or near zero within the first few months of getting the vaccine, unless the person had previously received a smallpox vaccine, scientists reported Saturday at the European Congress of Clinical Microbiology and Infectious Diseases in Barcelona.
The mRNA-1283 vaccine showed a higher immune response—including in seniors—than its currently licensed vaccine, called mRNA-1273.222. Response was higher against Omicron BA.4/BA.5 as well as the original SARS-CoV-2 virus.
The Covid pandemic marked the first time people armed with powerful scientific tools could study how the immune system awakens to and develops defenses against a new threat, in real time, in the global population.