Thank you to everyone who showed up for the talk yesterday.
CV-19 has not disappeared and it isn’t going to. Some parts of the world, primarily in Asia, are experiencing substantial waves. And China is still locking people in their houses in a futile attempt to suppress the virus. I expect we will see some bumps in cases here, especially if we continue with stupid testing policies. But I think at least in most developed countries the response has become more rational and accepting of our inability to eradicate CV-19.
This paper from Denmark looked at reinfection rates. Protection against subsequent infection was strong, at least as good as that offered by vaccination. Protection against reinfection appeared to be better in people who had symptomatic initial infections and in younger age groups. The protection lessened against Omicron and as with vaccines, appeared to lessen a fair amount after around six months. (SSRN Paper)
Bulgaria chimes in with some additional research on reinfections, also finding substantial protection, particularly against more severe outcomes, although vaccination appeared to provide better protection agains serious disease than did an initial infection. Reinfections were more likely with the Delta strain emergence. (Medrxiv Paper)
This study from Finland looked at vaccine effectiveness among those 70 or older in Finland. Vaccine effectiveness was over 90% in this group in regard to hospitalizations in the first couple of months after vax and declined slightly by the six month, but was restored to over 90% by a booster. (Medrxiv Paper)
A somewhat different topic is why some people appear more infectious than others. This paper explores the role of air acidity. CV-19 and influenza are both enveloped viruses and a number of factors may contribute to degradation of the envelope, including acidity. In typical air, influenza was found to degrade far faster than CV-19, which may contribute to CV-19’s apparent higher rates of transmissibility. It is apparent by now that CV-19 has an impressive ability to remain in the environment in viable form for an extended time. (Medrxiv Paper)
England had a substantial Omicron wave which is ongoing. This paper details some characteristics of that wave, which include a lessening of infection rates among children and an increase among the elderly. (Medrxiv Paper)
Kind of an interesting study on mortality rates among long-term care residents in Sweden. Mortality increased initially among those infected with CV-19, but then declined to below that of uninfected residents, indicating a pull-forward effect of deaths among those most likely to die in any event. (Medrxiv Paper)
More on long-term care residents in this study on vaccine effectiveness, which has the typical finding that by 3 months effectiveness against both infection and hospitalization declined, but was restored to a higher level following a booster. (Medrxiv Paper)