Coronavirus Research Tracking - 2 September
booster vaccines, risks from Covid-19, long Covid, spotting misinformation
This week in vaccine research the uncertainty about the effectiveness of Omicron-based vaccine boosters.
In non-vaccine research, Covid-19 can increase the risk of developing (or the severity of) other health conditions. Some cases of long Covid match the clinical definition of ME or chronic fatigue syndrome. More studies on immunity from reinfections. And, showing misinformation techniques could help reduce the spread of misinformation.
The Research Tracker is prepared by Dr Robert Hickson for the Science Media Centre.
Vaccine-related papers
Updated mRNA booster vaccines
A news article published in Science discusses the features of the updated Moderna and Pfizer booster vaccines. These are bivalent vaccines, including both the ancestral spike protein as well as the Omicron BA.1 spike protein.
The article notes that the impact of these boosters is unknown due to limited clinical data. The need for an Omicron-specific vaccine is still being debated by some scientists and clinicians. Trials of BA.4/BA.5 vaccines are also underway.
A meta-analysis of studies of neutralisation activity after vaccine booster doses was used to predict effectiveness of future booster vaccines. It concludes that a variant-modified booster could provide a 5% improvement in protection compared with another dose of the original vaccine. However, the effectiveness will depend on the pre-existing immunity to a circulating variant.
The paper suggests that the lower the pre-booster immunity, the greater the impact of a variant booster. Better protection would occur if the booster uses a spike protein that is antigenically similar to the current variant(s).
The authors acknowledge that there is currently very limited information on the effect on neutralisation of variant-based boosters. Their analyses also only focus on antibody neutralisation rather than cellular immunity. The paper has not yet been peer reviewed.
Hypersensitivity to polyethylene glycol doesn’t preclude receiving the Pfizer vaccine
A small New Zealand study found that people hypersensitive to polyethylene glycol had no serious adverse reactions to the Pfizer/BioNTech vaccine. Polyethylene glycol is present in this vaccine, but is of a lower molecular weight than that usually associated with an allergic reaction.
Eleven adults with presumed hypersensitivity to PEG received their first vaccine dose under medical supervision after receiving antihistamines. None experienced anaphylactic shock, although three had minor reactions that did not require medical interventions. All later received the second dose without serious adverse reactions. The paper was published in Internal Medicine Journal.
Non-vaccine-related papers
Evolving knowledge about T cell responses
A recent review discussed what is known about T cell responses to SARS-CoV-2, and how knowledge has changed as the pandemic proceeded. It identifies further areas of research into cellular immunity that are still required. The paper was published in Immunity.
Increased risks of some psychiatric conditions after Covid
Analysis of nearly 1.3 million patient medical records found that the risks of some psychiatric conditions were higher two years after getting Covid-19, compared with pre-pandemic levels. These included psychotic disorder, cognitive deficit, dementia, and epilepsy or seizures.
In contrast, increases in mood and anxiety disorders after an infection appeared to be temporary, with their incidence two years after an infection similar to pre-pandemic levels. Children had lower risks of developing psychiatric disorders than adults.
Asymptomatic cases will have been under-represented in the health records examined. The study focused on prevalence rather than severity of the course of the disorders. The study also focused on those who had Covid early in the pandemic, and so many had not been vaccinated. Vaccination, which can reduce symptom severity, could result in a lower risk of developing psychiatric disorders. The paper was published in The Lancet Psychiatry.
Potentially increased risk of metabolic disorders after Covid
A Swiss study of army recruits suggests that young healthy people who recover from mild Covid-19 may have a greater risk of developing metabolic disorders and cardiovascular problems. This is based on finding increased body mass index, higher lipid levels in blood, and reduced physical endurance six months after recovering.
The study included just under 100 young adults who had had Covid-19, and 300 without Covid or who were asymptomatic. Most (>90%) of the participants were male, with an average age of 21 years. Participants had not been vaccinated when the study started. The paper was published in The Lancet Infectious Diseases.
A commentary in the same issue of the journal notes that this study indicates that risk factors of vascular damage may provide predictors of who could develop long Covid.
Covid-19 can increase risk of hospitalisation & death from other health conditions
A UK study found that severe Covid-19 was associated with increased risks of hospitalisations and deaths due to a variety of non-Covid pulmonary and other diseases. Mild Covid was also associated with a modest increase in risk to all-cause mortalities. There was some evidence that vaccination may reduce these risks, but that needs further investigation.
The study used information from the UK Biobank, which has about half-a-million participants. Being observational, it established a correlation but not causation between Covid-19 and increased risks of hospitalisation and death. The paper has not yet been peer reviewed.
Some long Covid cases match chronic fatigue syndrome
A German study found that some adults with long Covid meet the clinical definition of myalgic encephalomyelitis/chronic fatigue syndrome. Nineteen of 42 adults with long Covid displayed symptoms consistent these conditions. No effective treatments for these are yet available.
The study was small, and did not include uninfected people or those without long Covid. The paper was published in Nature Communications.
BA.1 and BA.2 infections can provide reinfection protection against subsequent variants
A short paper published in the New England Journal of Medicine reports that in Portugal a prior infection reduces the risk of a subsequent BA.4 or BA.5 one. An earlier BA.1 or BA.2 infection provided the greatest protection from a BA.4/BA.5 infection.
The study wasn’t able to determine if this higher level of protection was due to similarities between Omicron subvariants, or just because BA.1 and BA.2 infections were relatively recent compared with Delta and Alpha. However, the study indicates that, contrary to some other studies, BA.1 and BA.2 infections do provide protection from reinfection with another (sub)variant.
Infections may provide 6 months protection from reinfection
A study of healthcare workers found that antibodies generated by an infection generally provide good protection for about six months. At least if the next variant is antigenically similar to the first. During the study, involving 400 participants, ten of the eleven new infections occurred in previously uninfected people.
Antibody levels varied between participants, but women and those over 40 tended to have higher levels. Levels generally declined in the first three months after an infection, but then stabilised. Only 6% of participants sero-reverted (antibodies became undetectable) over the study period.
The study was conducted between July 2020 and August 2021. Participants tended to be younger and relatively healthy. The paper was published in mBio.
Antigens could predict Covid severity
Plasma levels of the viral nucleocapsid antigen may be a good predictor of Covid-19 severity. The average antigen level was three times higher in patients requiring supplemental oxygen than those who didn’t. Very high antigen levels were associated with a greater risk of pulmonary problems and a longer hospital stay.
Men tended to have higher nucleocapsid levels than women. The study involved 2540 participants, but antigen levels were not measured at the same time in all patients, and some had received Remdesivir. The paper was published in Annals of Internal Medicine.
Psychological inoculation
“Psychological inoculation” could reduce the risk of spreading misinformation on social media. This involves sharing information on how people may be misinformed. Seven experiments, using explanatory videos, demonstrated that they improve people’s abilities to recognise manipulation techniques used to spread misinformation.
Six of the experiments were laboratory based, but the seventh was done using YouTube. It found that the videos improved identification of manipulation techniques by an average of 5%.
The YouTube trial only studied the effects for 24 hours, so the longer term effectiveness is unknown. The study also didn’t test if learning about one manipulation technique improved the ability to recognise other techniques, nor whether the risk of being influenced by misinformation is reduced. The paper was published in Science Advances.
The NZ Science Media Centre provided an expert reaction to this research.