Coronavirus Research Tracking - 30 September
Getting boosted soon after an infection, myocarditis, increased risks of type 1 diabetes and heart problems after Covid, wastewater testing, new variants
This week in vaccine research, a third vaccine dose soon after an infection may not be useful, and myocarditis that can sometimes develop in young people after an mRNA vaccine may clear up within 3 months.
In non-vaccine research, increased risks of type 1 diabetes and cardiac problems after an infection. Possible indicators for increased risk of long Covid. Narrowing down the search for people with persistent rare variant infections using wastewater. Becoming re-infected in less than three months may not be rare. And, a range of new variants are being monitored.
The Research Tracker is prepared by Dr Robert Hickson for the Science Media Centre.
Vaccine-related papers
A booster dose soon after an infection may have little benefit
A third mRNA vaccine dose shortly after an infection may not improve the antibody response. Antibody and B-cell responses in relation to a third dose were compared in people who had no prior infection, a recent infection, and an infection after boosting. Responses were monitored for two months after the third dose. Infections within six months of the third dose were classed as a prior infection.
For those with a recent prior infection (two to six months earlier) antibody and B-cell responses did not increase after a third vaccine dose. This was more noticeable in those who had a third dose sooner after the infection. Only 66 adults participated in the study, with only 11 each having an infection before or after the third vaccine dose. Other immune responses were not investigated. The paper was published in Cell.
Vaccine-related myocarditis in young people may usually resolve itself within 3 months
A small study found that most young people who developed myocarditis after an mRNA vaccine dose recovered within three months. The study was based on a survey of people who had a report filed in the US Vaccine Adverse Event Reporting System. Of 393 respondents who had a follow-up assessment by their healthcare provider, 81% were considered fully recovered, and another 14% improved.
About half the respondents reported ongoing depression or anxiety even if myocarditis symptoms had gone. There are no clear guidelines for following up myocarditis and the study found very variable reporting in the health assessments. Not all myocarditis cases will have been reported to VAERS. The paper was published in The Lancet Child & Adolescent Health.
Non-vaccine-related papers
For at-risk Covid patients a monoclonal antibody may be a better treatment option than the antiviral molnupiravir
For non-hospitalised Covid-19 patients a UK study found that treatment with a monoclonal antibody (sotrovimab) was more effective in preventing severe symptoms than the antiviral molnupiravir. Those treated with the antibody had about half the risk of developing severe Covid-19 as those receiving the antiviral, when taking account of a range of factors.
Participants in the study were identified as at greater risk of developing severe Covid-19, due to having particular diseases or medical conditions. The paper has not yet been peer reviewed.
Potentially increased risk of type 1 diabetes in young people after Covid-19
A US study involving one million paediatric patients (under 18 years) found that those who had had Covid-19 were more likely to develop type 1 diabetes in the next six months than similar patients with other respiratory infections. Covid patients had about twice the risk in the six months after an infection.
Post-infection diabetes diagnoses were low for both groups; 0.043% in Covd cases, and 0.025% in the control group. Other factors that could influence development of type 1 diabetes could not always be excluded. The paper was published in JAMA Network Open.
Mild cardiac problems may be common after recovery from Covid-19
One year after recovering from Covid-19, 57% of participants in a study were found to have persistent cardiac problems. The abnormalities were relatively mild. Cardiac inflammation due to the infection is suspected to be one cause.
Participants all had relatively mild Covid-19 that did not require a hospital stay. The study was relatively small, with 346 adult participants. The paper was published in Nature Medicine.
Some plasma proteins may indicate long Covid risk
A small study of healthcare workers found that protein changes in plasma shortly after an infection could help identify those most at risk of developing long Covid. Ninety one proteins were studied, of which 12 showed differences in abundance between infected and uninfected participants in the six weeks after an infection.
The abundance levels of six proteins were found to be associated with persistent Covid symptoms. The authors suggest that these may be useful biomarkers for long Covid risks.
Twenty nine participants had a confirmed infection, 11 of whom developed persistent Covid symptoms. Participants were monitored for 12 months after their infection. A control group of 102 uninfected workers also regularly had plasma proteins sampled. All infected participants had relatively mild Covid-19, and the study is based on healthcare workers infected early in the pandemic. The paper was published in eBioMedicine.
Wastewater surveillance can sometimes trace rare variants very close to their source
A Nature news article describes how a new and rare variant was traced through wastewater sampling to an office with 30 employees. The research was designed to find novel rare variants that persist for a long time in possibly immunocompromised people, and could lead to the next outbreak.
Sampling, over months, of different wastewater catchments helped narrow the search, in Wisconsin, to the office. Not all employees have been tested to date, so the infected individual remains unidentified. The gene sequencing method screened out the most common variants to help pick up rare novel ones.The lead researcher noted that they had attempted this before, but the variant disappeared before they tracked it to the source. A paper on the study is being prepared.
Re-infection, though rare, can occur within weeks after an Omicron infection
A French study found that one quarter of people with an Omicron infection were re-infected within 90 days by a sub-variant. Out of nearly 30,000 infected with an Omicron variant between November 2021 and July 2022, 188 (0.7%) were re-infected. The genomes of the viruses were sequenced to determine if they were separate infections. Six were reinfected within 30 days, 28 (15%) within 60 days, and 50 (26.6%) within 90 days. Sixty to 90 days is the current official time period to define a re-infection.
The study had only a small number of re-infections, and in some cases co-infections may have occurred in those who appeared to be quickly re-infected. The paper was published in Emerging Infectious Diseases.
Viable virus may persist for 2 weeks in some people
A small study found that replication-competent virus could be recovered from infected people 10-to-14 days after symptom onset. The study involved 95 infected adults who had relatively mild Covid-19. Presence of the nucleocapsid protein in sera was found to be a good predictor of virus viability. Viability was assessed using cultured cells.
The authors recommend testing for the presence of the nucleocapsid protein to determine if a person may still be infectious. A larger scale study is still required. The paper has not yet been peer reviewed.
New variants
A news article in Science discusses recent Omicron sub-variants that appear to be better at avoiding the immune system. Some appear to have independently converged on the same immune evasion mutations. One, BA.2.75.2, is already spreading in India, Singapore and Europe. A derivative of BA.5, BQ.1.1, is also spreading in some countries. It is not yet known whether they will cause more severe Covid-19, or how well existing vaccines will work against them.
In another study, mutations at position 346 in the spike protein of sub-lineages of BA.4 and BA.5 were shown to result in greater immune evasion. A change from the amino acid arginine to one of three other amino acids resulted in lower (about 2.5-fold) neutralisation by sera from vaccinated (with CoronaVac) people, those infected with previous Omicron sub-variants, and selected monoclonal antibodies. At least eight newer sub-variants have these mutations, including BA.4.6.
Numbers of samples for some of the neutralisation tests were small. The paper was published in The Lancet Infectious Diseases.
The emergence of new variants is also discussed in an article in Science.