New studies of recovered Covid-19 patients dampen the hope of long-lasting immunity and thus the long-term effectiveness of a possible vaccination.
Blood tests of the first corona patients in Germany, who were treated at Munich Clinic Schwabing at the end of January, showed a significant decrease in the number of so-called neutralizing antibodies in the blood, reported Clemens Wendtner, chief physician of the local clinic for infectious diseases.
“In four of the nine patients, we see falling neutralizing antibodies in a very special test that can only be carried out in a high-security laboratory,” said Wendtner. “The extent to which this has an impact on long-term immunity and vaccination strategies is still speculative, but must be monitored critically as it progresses.” However, it suggests that a new infection is possible after the illness.
This must be observed further, said Wendtner. In addition to the so-called B-cell-associated immunity measured via antibodies, so-called T-cell immunity is also relevant for long-term immunity. If patients lose neutralizing antibodies, this immunity may provide protection. T-lymphocytes can kill virus-infected cells in a targeted manner once they have met their opponent beforehand.
Wendtner’s findings are in line with the experiences of other scientists and study results. Chinese researchers reported in the journal “Nature Medicine” that the antibodies decreased sharply after two months, especially in patients with a symptom-free course, but the values also fell significantly in actually ill patients. Patients with few symptoms also had fewer antibodies and therefore a weaker immune response.