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Florian Krammer conducts research at Mount Sinai’s Icahn School of Medicine in New York (USA) and developed one of the first laboratory tests on antibodies to the new virus shortly after the coronavirus pandemic began. Using blood samples taken from patients at Mount Sinai Hospital, the research team examined the course of the spread in the city, which was one of the first to be severely affected outside of China.
They divided the samples into two groups, namely one that was treated in the hospital in the emergency room (“UC group”) from February to July, and another that underwent routine examinations there (“RC group”). . ). In total, more than 10,000 plasma samples were obtained, which were then tested for antibodies against SARS-CoV-2.
From mid-February
From the week of February 17-23, 2020, the first positive results were found in the UC group samples. This is a little before the first known infection in New York, which was recorded at Mount Sinai Hospital on March 1. The fact that the virus was circulating in the internationally intensely connected metropolis ahead of schedule comes as no surprise to Krammer, as he told the APA.
Until mid-March, the positive sample rate in the UC group remained between 1.4 and 3.2%. This percentage reached its peak – after a significant increase from the week through March 22 – then around April 19 with nearly 62%. A decline followed by the end of May, which stabilized at just over 20 percent until July. In the RC group, the values were significantly lower, but around April 19 they reached 20%, which was more or less the same.
Because the RC group better represents the total population of New York and the post-peak results fit well with the comparison group and values from other studies, scientists estimate that by the end of May about one fifth of city dwellers – or 1 , 7 of the 8.4 million New Yorkers have been infected. However, they were far from herd immunity. According to the researchers’ estimates, this would require a percentage of HIV-positive people of around 67%.
Mortality at 1%
Considering the 16,674 deaths from Covid-19 recorded in New York to this point, Krammer and his team come to an infectious death rate (IFR) of 0.97%. This value is therefore well above the IFR recorded with the outbreak of the H1N1 influenza virus (“swine flu”) in 2009. At the time, the value was estimated to be between 0.01 and 0.001 percent, the authors write. researchers.
For Krammer, the high death rate in New York is mainly due to “health care overload.” Also, you had to deal with a completely new disease “that you didn’t know how to best treat it”. Also, there was a “relatively old population structure,” Krammer explained: “Also, you didn’t know the virus was there. If you had gone into lockdown earlier, it would have been better. But we were surprised.”
Overworking increases the mortality rate
For the virologist, the most important message of the analysis on New York is “that if the health system is overloaded, the IFR goes up”. So, if there are too many cases in general and the intensive care units are correspondingly full, more people will die from Covid-19. This image spans the pandemic in all countries.
Analysis of the samples also showed that the immune defense apparently remained relatively stable. Krammer and colleagues recently demonstrated this in more detail in a study in the journal “Science”. As a result, the number of antibodies to the new virus will remain at a higher level for at least five months, the researchers write. Furthermore, it has been shown that these could continue to neutralize the authentic SARS-CoV-2 pathogens. Krammer: “The antibody response looks ‘normal’ and is relatively stable.”
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