The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for Covid-19, the illness caused by the virus.
Covid-19 severity linked with diet
People on meat-free diets had lower odds of contracting moderate to severe Covid-19, according to a six-country study published on Monday in BMJ Nutrition, Prevention & Health. Plant-based diets were tied to a 73% lower risk of severe disease, researchers found in a survey of 2,884 healthcare providers who cared for Covid-19 patients. Combining those on a plant-based diet and people who also ate fish but no meat, researchers found 59% lower odds of severe disease. The study cannot prove that specific diets protected against severe Covid-19, and the diet did not appear to lower the risk of becoming infected. But plant-based diets are rich in nutrients, vitamins and minerals that are important for healthy immune systems, the researchers noted, and fish provide vitamin D and omega-3 fatty acids, which have anti-inflammatory properties. Healthy eating, however, has been problematic during the pandemic, according to two presentations this week during a virtual meeting of the American Society for Nutrition. Consumption of healthy foods such as vegetables and whole grains declined, according to researchers who compared the diets of more than 2,000 Americans before and during the pandemic. In a separate study, researchers who collected dietary data in June 2020 for 3,916 US adults found many had increased their consumption of unhealthy snacks, desserts and sugary drinks during the pandemic. “Individuals may need help to avoid making these dietary changes permanent,” said Dr. Sohyun Park of the US Centers for Disease Control and Prevention, coauthor of the latter study.
No serious problems with AstraZeneca vaccine in Scotland
A study of side effects from AstraZeneca’s COVID-19 vaccine in Scotland found only an association with a largely harmless bleeding condition and no link to the potentially deadly venous clotting in the brain, known as CVST, which has caused concern in Europe and led to pauses in its use. Researchers who tracked 5.4 million people in Scotland found roughly one additional case of idiopathic thrombocytopenic purpura (ITP) per 100,000 people after the first AstraZeneca shot. ITP is a treatable condition of low platelet count and has not caused any deaths among the 1.7 million recipients of the vaccine in the study, the authors reported on Wednesday in Nature Medicine. Due to the rarity of CVST, the Scottish study may have been too small to allow for any conclusions, coauthor Aziz Sheikh of the University of Edinburgh told a media briefing. “The overall message is just the rarity of these results,” said Sheikh. “This is reassuring data.”
Aspirin does not help hospitalised covid-19 patients
Aspirin did not improve survival or reduce disease severity in a study of nearly 15,000 patients hospitalized with Covid-19. Researchers had hoped that because aspirin helps reduce blood clots in other diseases, it might be helpful in Covid-19 patients who are at a higher risk for clotting issues. Patients randomly assigned to receive 150 milligrams of aspirin once a day did have fewer blood clots, but no lower risk of becoming sicker and requiring mechanical ventilation or better odds of being alive after 28 days. And they had a higher risk of major bleeding complications, a not uncommon issue with aspirin therapy. They did have slightly better odds of getting out of the hospital alive, researchers reported on medRxiv on Tuesday ahead of peer review. But “this does not seem to be sufficient to justify its widespread use for patients hospitalized with Covid-19,” said Peter Horby of the University of Oxford, co-chief investigator of the trial.
Covid-19 control policies still needed in warm weather
In the absence of lockdowns and social distancing, weather and crowding have the biggest impact on Covid-19 spread, a new study found. But even if virus transmission tends to be somewhat lower in warmer conditions, summer weather “cannot be considered a substitute for mitigation policies,” because population density matters more than temperature, according to the report from Imperial College London published on Wednesday in PNAS. Warmer regions should not expect to ease mobility restrictions before colder regions, especially because “warmer regions tend to have higher population densities – for example, the population in Florida is more densely packed than in Minnesota,” coauthor Will Pearse said in a statement. Lockdowns have stronger effects than either temperature or population density, his team reported. Because temperature changes have a much smaller effect on transmission than policy interventions, “while people remain unvaccinated, governments mustn’t drop policies like lockdowns and social distancing just because a seasonal change means the weather is warming up,” said coauthor Dr. Tom Smith. The study also suggests “that lower autumn and winter temperatures may lead to the virus spreading more easily in the absence of policy interventions or behavioral changes.”
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