Florian Krammer is doing research at the Icahn School of Medicine at Mount Sinai in New York (USA) and developed one of the first antibody laboratory tests for the new virus shortly after the coronavirus pandemic began. Using blood samples from patients from the Mount Sinai Hospital, the research team looked back at 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 care (“UC group”) from February to July, and another that was subjected to routine examinations there (“RC group”). ). In total, more than 10,000 plasma samples were obtained, which were then examined for antibodies against SARS-CoV-2.
From mid-February
From the week of February 17 to 23, 2020, the first positive results were found in the samples of the UC group. This is a little earlier than the first known infection in New York, which was recorded on March 1st at Mount Sinai Hospital. The fact that the virus was circulating in the internationally intensively connected metropolis earlier than assumed does not surprise Krammer, as he explained to the APA.
Through mid-March, the rate of positive samples in the UC group remained between 1.4 and 3.2 percent. This proportion reached its peak – after a significant increase from the week up to March 22nd – around April 19th with almost 62 percent. A downturn 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 reached the 20 percent mark around April 19, which was roughly the same.
Since the RC group better represents the total population of New York and the results after the peak fit well with the comparison group and values from other studies, the scientists estimate that by the end of May around a fifth of city dwellers – or 1.7 of the 8.4 Millions of New Yorkers – were infected. Nevertheless, they were far from herd immunity. According to estimates by the researchers, this would require a proportion of seropositive people of around 67 percent.
One percent mortality
In view of the 16,674 Covid 19 deaths registered in New York up to this point, Krammer and his team come to a death rate among the infected (IFR) of 0.97 percent. This value is thus well above the IFR that was registered with the outbreak of the H1N1 influenza virus (“swine flu”) in 2009. At that time, the value was an estimated 0.01 to 0.001 percent, write the researchers.
For Krammer, the high death rate in New York is primarily due to the “overloading of the health system”. In addition, you had to deal with a completely new disease “which you didn’t know how to best treat”. In addition, there was a “relatively old population structure,” explained Krammer: “You also didn’t know that the virus was there. If you had gone into lockdown earlier, it would have looked better. But we were surprised. “
Overwork increases death rate
For the virologist, the most important message from the analysis on New York is “that if the health system is overloaded, the IFR goes up”. So if there are too many cases overall and the intensive care units are correspondingly full, more people will also die of Covid-19. This picture runs through the pandemic across countries.
The analysis of the samples also showed that the immune defense apparently remains relatively stable. Krammer and colleagues recently published this in more detail in a study in the specialist journal „Science“ shown. Accordingly, the number of antibodies against the new virus will remain at a higher level for at least five months, the researchers write there. In addition, it was shown that these could continue to neutralize authentic SARS-CoV-2 pathogens. Krammer: “The antibody response looks ‘normal’ and is relatively stable.”
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