Researchers examined blood donations in December and early January and found evidence of novel coronavirus antibodies in at least 84 samples from nine states – indicating that people were infected with the coronavirus.
Many people wonder if they had the coronavirus at the beginning of the epidemic, or if the virus was circulating even before people knew it.
It’s hard to know unless someone took a coronavirus test at the time – something that clearly didn’t exist. The symptoms are similar to many other infections like the flu: cough, fever, body aches, sore throat maybe.
Columbia University Infectious Diseases Specialist Dr. Ian Lipkin said that without a sample taken at the time of infection or immediately, it would be impossible to know if anyone was infected at the time.
Antibody tests may indicate a past infection, but not when it is infected.
“You can’t tell the difference between someone being infected in December or someone infected in March or April.”
A person’s immune response to a viral infection, such as Covid-19, changes over time. Some studies have shown that antibody responses progress immediately after infection and then change over time. It is not yet known how long the human body maintains an immune response to coronavirus infection.
“There are tests that show signs of a very recent infection in the first few weeks of infection, but after that you can’t really tell,” Lipkin said. The only exception would be if someone has had a blood test before, which shows that it is negative for the virus.
Blood donation can be an important source of information about when the virus began to spread, the study shows, according to CDC and Red Cross researchers. The findings also highlight the value of blood donations as a source for SARS-CV-2 surveillance, they wrote in a report on Tuesday. SARS-Cov-2 is the scientific name for the coronavirus that causes Covid-19.
Blood donations collected from last year can be tested for antibodies, although the type of test can be important. CDC and Red Cross researchers have noted that some other coronaviruses cause common colds and tests can mistakenly detect infection with that virus.
“We want to know exactly how long the virus has been spreading,” Lipki added.
“People are trying to figure out when this first came out of China.”
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