Hi Everyone - time to put that PhD to work!
The article is interesting. If you recall, there was a pre-print a couple of weeks ago out of Israel that suggested that immunity from the Pfizer vaccine was inferior to natural immunity associated with a covid-19 infection. The article is concerned with the longevity of the immunity conferred by mRNA vaccines and a 25mg dose of Moderna in particular.
<<Comparison of vaccine-generated immune memory to immune memory of persons infected with SARS-CoV-2 is of value, as studies have indicated natural immunity is 93% to 100% protective against symptomatic reinfection for 7-8 months.>>
Here is the nub of the article - what protects better, naturally-acquired immunity or vaccine-generated immunity?
<<After SARS-CoV-2 infection, immunological memory has been observed for ≥8 months for CD4+ T cells, CD8+ T cells, memory B cells, and antibodies. The immune memory in response to SARS-CoV-2 infection exhibits a relatively gradual decline that partially stabilizes within 1 year.>>
So if one catches covid, the immunity wanes over the course of a year before stabilising. The authors also note separately that this natural immunity is less effective against variants of concern, such as delta.
The authors ran a clinical trial with 33 subjects using the 25mg dose of Moderna's vaccine, and took blood on four separate occasions between day 1 and day 209. Relevant markers of immunity were found in all subjects 6 months after double-vaccination (days 1 and 29), and the researchers determined that the immune response of the subjects with Moderna's vaccine was, at 7 months, similar to those who had acquired natural immunity through infection:
<<Anti-spike antibody and CD4+ and CD8+ T cell responses generated by 25-μg mRNA-1273 vaccination were multifunctional, durable, and comparable in magnitude to those induced by natural infection.>>
One of the important findings is that:
<<Data reported here are encouraging demonstrations of the potential of RNA vaccines to generate durable T cell and antibody immune memory, including at lower vaccine doses.>>
The authors note that this will make vaccines go further and may also reduce reactions to the vaccines themselves.