The wave of breakthrough cases of Delta variant has indicated a declining VE against infections by the covid vaccinations, however, there has not generally been a decline in VE on severe disease which remains high. This is consistent with the post-infection and post-vaccination period for this type of virus resulting in a waning of circulating antibodies, but retaining of cellular immune memory (B and T cells) which will respond upon seeing the antigens again and keep most breakthrough infections mild.
One question that has been asked is whether, once infected, vaccinated people are equally likely to transmit the virus to others as unvaccinated people are.
There are now two studies indicating that vaccinated people are less likely to spread the disease, although they are still capable of doing so.
First in Singapore they showed that despite having similar peak viral loads between vaxed and unvaxed Delta cases, the viral load is cleared faster in the vaccinated (Consistent with having immune memory that gets activated and boosts Antibodies again, before the unvaccinated person's immune system turns on).
https://www.medrxiv.org/content/10.1101/2021.07.28.21261295v1Now the latest study in the US shows that at equal viral loads, when they actually cultured virus, the vaccinated person less frequently has infection-capable cultured virus compared to the unvaxed at the same viral load. This difference is particularly pronounced at lower viral loads. Given that Asymptomatic cases are likely to have the lowest viral loads, it tells you that an asymptomatic vaccinated person is much more unlikely to spread the virus than an unvaccinated asymptomatic person. This can give people a little peace of mind while watching out for the development of symptoms.
https://www.medrxiv.org/content/10.1101/2021.08.20.21262158v1
Topic: Although many breakthroughs cases, Vaccinated still less infectious than unvaxed (Read 989 times)