Coronavirus: US case of reinfection ‘may affect vaccine research’
- Scientists say a patient in a Seattle nursing home tested positive for a mutated strain a few months after recovering from an earlier variety
- Findings suggest that the antibodies formed after the first infection did not offer strong protection against the second, team says
But other researchers have said that the mutated strain of the coronavirus in the study so far does not appear to have a big effect.
The patient in the US study was from Seattle and fell severely ill in March after contracting the virus with genes linked to the first strains of Sars-CoV-2, the official name of the coronavirus, detected in the central Chinese city of Wuhan.
In August, the patient returned to the hospital with a different strain of the virus carrying D614G, a mutation that was not seen in the first infection.
“These results could have important implications for the success of vaccine programmes based on the Wuhan strain,” said the researchers led by Jason Goldman with the Swedish Medical Centre in Seattle in a non-peer-reviewed paper posted in medRxiv.org on Friday.
Goldman’s team said their patient, whose sex was not specified, was a nursing home resident in his or her sixties who might have first caught the virus from a staff member who returned from the Philippines with a respiratory infection.
In March, the patient was hospitalised for over a month with severe pneumonia associated with Covid-19, the disease caused by the coronavirus.
After recovering, the patient went to a new nursing facility where several other residents had coughs. In August, after two weeks with a dry cough and general weakness, the patient was sent back to hospital and tested positive again, this time for the coronavirus strain with the D614G mutation.
Chen told the Global Science and Life Health Forum in Beijing earlier this month that every day her team monitored the international database of viral genomes sequenced in different countries.
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She said researchers were trying to determine the structural or functional changes caused by these mutations, including D614G, which occurred in almost every sequence recently updated from around the globe.
“[But] so far the impact [of D614G] is estimated to be very small,” she said.
Goldman and his colleagues found the Seattle patient’s immune cells took 18 days – longer than expected – to respond to the second infection, which might suggest “a deficiency in the developing response to the reinfection”.
The antibodies developed during the second infection also had a stronger response to the D614G mutant variety than the Wuhan strain.
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The researchers said these were signs that the antibodies formed after the first infection did not offer strong protection against the second infection.
“Taken together, these findings suggest that poorly developed or waned antibodies against the D614G virus formed after primary infection in March were not protective against reinfection with the D614G spike variant acquired in July,” the paper said.
However, symptoms of reinfection such as fever were less severe in the Seattle patient, the paper said.
There have been many reports of possible reinfections from around the world, but only a few cases have been confirmed scientifically.
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Cases of reinfection with mutated strains could have implications for vaccines because nearly all the vaccines close to mass application were developed based on the coronavirus genome sequenced and released by Chinese scientists in January.
More than 100,000 volunteers throughout China, including diplomats, engineers and workers sent overseas, have already been given shots of vaccine candidates, according to Chinese authorities.
The hope is that antibodies from the vaccines will offer sustained protection against reinfection and various strains.
State-owned vaccine developer Sinopharm Group said there was some preliminary evidence of protection from its potential vaccines, including areas where the D614G mutation prevailed.
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But a team of US military scientists said widespread mutations such as D614G were rare.
In a paper published in the journal Proceedings of the National Academy of Sciences of the United States of America this month, the team said that though there was evidence that the mutation could increase the efficiency of viral transmission, the mutated strains still fell within the target range of nearly all vaccines under development.
“A single vaccine candidate should be efficacious against currently circulating lineages,” said the team led by Morgane Rolland with the US Military HIV Research Programme.
