COVID Booster: Genes responsible for symptoms, COVID breast milk, AI predictions and the nocebo effect.

Genes may be key to loss of taste and smell due to COVID-19

A sudden loss of taste and smell are common COVID-19 symptoms to watch out for, but new research published in Nature Genetics has suggested that our genes play a part in which unlucky people’s senses stop functioning due to the virus.

Researchers from 23andMe collected surveys and genetic data from over 1 million people and found that those with distinct sets of variants near two genes – UGT2A1 and UGT2A2 – were 11% more likely to experience a loss of taste or smell following infection.

Both genes encode for enzymes which are made in cells that line the inside of the nose and are involved in eliminating odorants – compounds which have a smell or odour – that bind to receptors involved in smell detection.

These findings provide clues to understanding the biological mechanisms underlying the COVID symptoms.

Why don’t people with COVID-19 symptoms get tested?

According to a new study of 4.3 million adults in the UK, mild symptoms, poor knowledge of nearby testing sites and certain demographics have been identified as barriers to COVID-19 testing.

The study, published in PLOS Global Public Health, found that the most common factor among people who wanted a test  but didn’t have one  was not knowing where to go. This increased for each decade older a person was and for every four years less  education they had.

Symptomatic people were more likely not to get tested if they had just one symptom (27.1%) compared to more symptoms (14.6%), and if those symptoms lasted two or fewer days (30.1%) compared to longer-lasting symptoms (14.6%).

Mums can’t transmit COVID through breast milk

Of all young children infected with COVID-19 around the globe, about 50% of cases are reported in infants. This adds another layer of stress for new mums – but a new study has shown that even if someone is infected with COVID-19, they cannot pass it on to their baby via breast milk.

The research team, led by the University of California, LA, analysed the breast milk from a cohort of 110 lactating women, specifically looking for markers of infectivity of SARS-CoV-2. Of these women, 65 had tested positive to COVID; 9 had symptoms but tested negative; and 36 had symptoms but had not been tested.

While the team found some genetic material of SARS-CoV-2 in the breast milk, it was only transiently present and could not be cultured from the samples.

“We found no evidence that breastmilk contains an infectious virus or that breastfeeding represents a risk factor for transmission of infection to infants,” they write in their paper, published in Pediatrics Journal.

Most vaccine side effects are due to a nocebo effect

US researchers have shown that up to two-thirds of common side effects of COVID vaccines are due to a negative version of the placebo effect, rather than actually being caused by the vaccine itself.

The study, published in JAMA Open Network, analysed 12 different clinical trials of COVID vaccines where 22,802 people were given a vaccine and 22,578 people were given a placebo containing an inactive salt solution.

More than 35% of placebo recipients reported adverse reactions like fever, headache and fatigue. In comparison, 46% of vaccine recipients reported at least one adverse effect.

But the analysis suggested that even among those who had received actual vaccines, 76% of all common adverse reactions could be pinned on the “nocebo effect” after the first dose, and 52% after the second dose.

“Non-specific symptoms like headache and fatigue – which we have shown to be particularly nocebo sensitive – are listed among the most common adverse reactions following COVID-19 vaccination in many information leaflets,” says senior author on the study, Ted J. Kaptchuk, from Harvard Medical School.

“Evidence suggests that this sort of information may cause people to misattribute common daily background sensations as arising from the vaccine or cause anxiety and worry that make people hyper-alert to bodily feelings about adverse events.”

Lead author Julia W. Haas, from the Beth Israel Deaconess Medical Center in Boston, notes: “Collecting systematic evidence regarding these nocebo responses in vaccine trials is important for COVID-19 vaccination worldwide, especially because concern about side effects is reported to be a reason for vaccine hesitancy.” 

Using AI and blood tests to predict COVID-19 survival

A single blood sample could predict whether a critically ill COVID patient will live or die weeks before the outcome, a new study suggests.

Published in PLOS Digital Health, the study looked at the levels of 321 blood plasma proteins, taken from 50 critically ill COVID patients in Germany and Austria. These proteins are known to capture the host response to COVID-19. The team then applied an artificial intelligence algorithm to look for an association between the proteins and survival.

They found 14 specific proteins with levels that changed in opposite directions for patients who survived and patients who didn’t. When fed to the AI, this information could be used to predict survival.

The team then tested the predictions on 24 patients; the AI correctly predicted the outcome for the five who died, and for 18 out of the 19 who survived.

While the study was small and more research is needed, this technique could help identify patients at the greatest risk of dying, as well as to see whether treatments are effective.