Cases are staying very low in Minnesota. If the state had the courage to do actual meaningful research, it would be doing large randomized re-tests of current positives to establish the false positive rate and it would be publishing the distribution of cycle thresholds. The thing to watch in the next couple of weeks is whether we see much of a case bump beginning in the south and Southwest. People like Andy “I should learn to keep my mouth shut” Slavitt and Dr. Osterholm, who I thought said he was done predicting, are back to terrifying people about the Delta or Indian variant. Unfortunately for them, the data may not even support strong transmissibility, much less more serious disease. But terrorists gonna terrorize.
Yet another piece of research on the effects of meteorological variables on transmission. (Nature Article) The researchers looked at temperature, specific humidity and ultraviolet radiation as factors in spread rates in most counties in the US from March 15 to December 31, 2020. Overall the meteorological variables were said to account for about 20% of the variation in spread rates, with humidity the largest factor. The effect was greater in the northern part of the US than the southern part. Lower temperatures, lower humidity and less ultraviolet radiation all appeared to favor greater transmission.
African-Americans appear to have more serious outcomes for CV-19 disease than do Caucasians, but much of this difference disappears when adjusted for health status. A new piece of research assesses relative mortality between African-American and Caucasian Medicare beneficiaries. (JAMA Article) The study found that while adjusting for clinical status and demographics still left about an 11% difference in mortality, once the hospital caring for the patient was taken into consideration, the difference disappeared. In other words, hospitals with poor outcomes for CV-19 treatment tended to treat more African-Americans.
Another study indicating that both vaccination and prior infection result in a strong and lasting adaptive immune response. (JI Article) The authors examined antibody responses in health care workers who had been infected and those who were vaccinated, whether infected or not infected. The study followed some workers for over a year. Vaccination boosted antibody responses even in those who had been infected before. Prior infection was associated with a low rate of reinfection, and vaccination lowered the reinfection rate further, to zero. Indicates that infection plus vaccination may result in the strongest adaptive immune response. And antibody protection seems to last for at least one year.
And more research to the effect that memory B cell response is critical to understanding the robustness of adaptive immunity. (Medrxiv Paper) In this study the authors found that memory B cells in both vaccinated uninfected and vaccinated infected persons were robust and able to detect and defend against the variants of concern. In individuals who previously had been infected, vaccination boosted and matured the memory B cell response, which was stronger than that found in uninfected but vaccinated individuals. This suggests that repeated challenge with the same pathogen boosts the overall response.
And yet another study on the limitations, severe limitations, of PCR testing. (JI Study) The research comes from a single large laboratory in Germany and covers most of 2020. Over 160,000 people were tested. Symptomatic people on average had lower cycle numbers, and thus higher viral load, than did asymptomatic ones. For the cutoff used to determine likely infectiousness, only 41% of “positive” tests actually indicated likely infectiousness. And the problem was worsened during the period in Germany when there was substantial testing of asymptomatic persons. As the authors say, using PCR tests to determine the prevalence of infectious individuals is inappropriate.