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Reno – Just 48 days after a positive test for SARS-CoV-2 and two meanwhile negative smears, a 25-year-old American contracted COVID-19 again. The second time even more violently than with the first illness. The at Lancet The case submitted for publication is the fourth within a few days in which a second infection with SARS-CoV-2 could be documented.
A team led by Kelvin Kai-Wang To from the University of Hong Kong had the first case on August 25th Clinical Infectious Diseases (2020; DOI: 10.1093 / cid / ciaa1275) presented. A 33-year-old man first contracted COVID-19 on March 26th.
At that time he had only suffered from coughing with sputum, sore throat, fever and headache for 3 days, but had been hospitalized for 3 weeks as a precaution. After two negative tests, he was released. On August 15 he entered Hong Kong from Spain. Completely surprisingly, he was noticed during a screening at the airport due to a positive smear. 142 days had passed since the first infection.
The patient was hospitalized again, but this time remained asymptomatic. Only the C-reactive protein (CRP), a general marker of inflammation, was slightly increased at 8.6 mg / l. Except for a hypokalaemia, the laboratory values were normal. Repeated x-ray examinations gave no evidence of pneumonia.
Serial examinations of the saliva showed that the viral load gradually decreased again. With the first infection, the antibody test turned out negative 10 days after the onset of symptoms. On the first day of the second hospitalization, the patient had no antibodies. Five days later, IgG antibodies appeared in the blood.
Kai-Wang To’s team was able to sequence the viruses from the two infections. The first time the patient was infected with a strain (clade 19A) circulating in China. The second virus was of US or European origin (Clade 20A).
The genetic differences were clear: in addition to a stop codon that led to the loss of 58 amino acids, there were 23 mutations, 13 of which were non-synonymous, i.e. led to a change in the amino acid sequence. The differences in amino acids between the two genomes involved different proteins.
Kai-Wang To rules out that the man was latently infected in the meantime. In the opinion of the microbiologist, the differences in the virus genomes, the long interval, the evidence of an active (albeit asymptomatic) infection with a rise in CRP and subsequent seroconversion speak clearly in favor of a second infection with a different version of SARS-CoV-2.
Shortly after the publication of the Hong Kong patient, virologists from the University of Leuven turned to the media with the case of a woman from Belgium: A 51-year-old woman had a fever, cough, chest pain, shortness of breath, muscle pain and a sudden loss of odor in March. and a sense of taste turned to her family doctor.
He had taken a nasopharynx smear in which SARS-CoV-2 was detected by a PCR test. The patient spent two weeks in quarantine at home and was then on sick leave for three weeks before returning to work.
The same symptoms reappeared in June 2020. 93 days had passed since the first infection. The nasopharynx smear was again positive for SARS-CoV-2. The second COVID-19 episode was less intense and only lasted a week. In July 2020, SARS-CoV-2 antibodies were detected in high concentrations. In August 2020, a nasopharynx smear was found to be PCR negative for SARS-CoV-2.
The Belgian team of doctors led by Marc van Ranst from the Catholic University of Leuven was able to carry out a genome comparison. 11 mutations were detected. The molecular analysis grouped the two virus isolates into different SARS-CoV-2 lines.
After the case from Belgium, virologist Marion Koopmans from Erasmus University, Rotterdam, told the news channel NOS that a second infection had also occurred in the Netherlands. It is an elderly patient with a weakened immune system. The virologist, who is prominent in the Netherlands, did not give details of the case.
The most recent case comes from the US state of Nevada. This is a 25-year-old patient who first tested positive for SARS-CoV-2 in a screening on April 18. According to the details now shared by Richard Tillett of the University of Nevada at Reno, the patient first had a sore throat, cough, headache, nausea and diarrhea on March 25th. The symptoms lasted for 3 days. After two negative smears on May 9th and May 26th, he was released from isolation.
Symptoms reappeared just two days later (May 28). On May 31, the patient received medical treatment for fever, headache, dizziness, cough, nausea, and diarrhea. A chest x-ray was negative and he was discharged home. Five days later, on June 5th, the patient presented again to the family doctor. He diagnosed hypoxia.
The patient was admitted to a clinic on the same day and treated with oxygen. In addition to shortness of breath, he suffered from myalgia and cough. A chest x-ray dated June 5 showed new blotchy bilateral interstitial shadows suggestive of viral or atypical pneumonia. One smear was positive for SARS-CoV-2. On June 6th, IgG / IgM antibodies to SARS-CoV-2 were found.
Tillett assumes that it is a second infection despite the short time interval. The genetic differences are too great for the new virus to have developed from mutations in the first pathogen during a latent phase. The mutation rate should then have been 83.64 substitutions per year.
With SARS-CoV-2, a rate of 23.12 substitutions per year has been observed so far. Both viruses belong to the same clade 20C currently prevalent in Nevada.
Tillett suspects that the patient was infected from a parent who also tested positive. A genome comparison of the pathogens was not carried out, however.
Why the patient was infected again and this time became more seriously ill is unclear. According to Tillett, he had no immune deficiency, was HIV negative and was not taking any immunosuppressive drugs.
Four re-infections that became known within a week naturally raise the question of whether this is a more common phenomenon. Tillett points to studies on other coronaviruses that suggest that immunity to coronaviruses could be lost after 1 to 3 years.
This was shown in an experimental study 30 years ago for the coronavirus 229E, one of the four harmless coronaviruses widespread worldwide. British researchers had infected 15 volunteers with 229E at the time. In 10 there was an infection, of which 8 developed a cold (these were the participants with the lowest antibody concentrations before the infection). In all test subjects there was an increase in antibody titers, which, however, fell again 12 weeks later.
A year later, the subjects were exposed again to 229E. Infection was detected again in 6 out of 9 people who were infected the first time. Nobody developed a cold this time, as KA Callow and colleagues reported in Epidemiology and Infection (1990;, 105: 435-446).
Even after infections with the first SARS-CoV, there was a gradual decrease in antibody titers, as reported by a team led by Nanshan Zhong from the Guangzhou Institute for Respiratory Diseases in Respirology (2006; 11: 49-53).
Serological screening showed that IgG titers, which had risen dramatically from day 15 of the disease, already peaked on day 60. It plateaued by day 180 and then gradually decreased by day 720. The researchers concluded that immunity to SARS-CoV-1 lasts for up to 2 years. Proof of this has never been provided, as the virus disappeared after a brief violent pandemic, which is currently not to be expected from SARS-CoV-2. © rme / aerzteblatt.de
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