Prioritizing Essential Workers for Vaccines Controls Spread. And More Science News

Compiled by veteran medical journalist Brian Owens, this roundup of some of the newest science on the COVID-19 pandemic, straight from the scientific journals, is presented by Hakai Magazine in partnership with The Tyee.

Prioritizing vaccines for essential workers helps control virus spread

Prioritizing essential workers for vaccination right after the most vulnerable elderly people is the best way to control the spread of COVID-19, according to a study that simulated different vaccination strategies. The researchers modelled scenarios involving various levels of outbreaks, vaccine supplies and mitigation measures like masking and found that strategies that took both age and essential worker status into account were the most effective at reducing the spread of the virus and deaths. The prioritization strategy should also be adjusted as conditions change, the researchers say.

Proceedings of the National Academy of Sciences, April 2, 2021

One-third of hospitalized patients are readmitted

Almost one in three patients hospitalized with COVID-19 end up back in the hospital within four months of being discharged, and 12 per cent die within the same timeframe, according to a new study from the U.K. The rates of hospitalization and death were four and eight times greater, respectively, than seen in a control group. The most common cause of readmission was respiratory disease, with heart, kidney and liver problems also reported. The risk of readmission was not confined to older people and was higher in ethnic minority populations.

British Medical Journal, March 31, 2021

School closures have only a small effect on virus transmission, so how do we open them safely?

Closing schools has only a small effect on the spread of COVID-19 compared with other community-based interventions like mask mandates, according to a simulation involving one million people based on the population of Ontario. Across the simulated scenarios, most infections were the result of community spread and less than five per cent of infections were acquired in schools, indicating that community-based non-pharmaceutical interventions should be prioritized ahead of school closures.

Two other studies demonstrate strategies for how to open schools safely while keeping infections to a minimum. One looked at two schools in the U.S. that reopened in September, and while they did see some infection, both were able to keep case numbers low and the transmission rate to 0.5, even while surrounding community transmission rates rose. The schools tested students and staff regularly, and required mitigation measures like mask-wearing, social distancing, and ventilation and air filtering. The researchers said that the regular testing was the key to keeping cases under control, as it allowed them to spot infections before they turned into outbreaks. Another study of a simulated classroom found that masks and ventilation were more important than physical distancing for controlling the spread — with those in place, more students can safely be in each classroom.

JAMA Network Open, March 31, 2021

Journal of School Health, March 25, 2021

Physics of Fluids, Feb. 24, 2021

The effects of the pandemic in Canadian long-term care

Efforts to control COVID-19 in long-term care homes in Canada led to unintended effects on residents, according to a report by the Canadian Institute for Health Information. Residents received less medical care and fewer visits from family, friends and caregivers, and more of them died than in previous years. During the second wave, COVID-19 infections increased by 62 per cent in long-term care, but the death rate fell from around 33 per cent to 20 per cent. Overall, 69 per cent of Canada’s deaths from COVID-19 have occurred in long-term care, much higher than the average of 41 per cent seen in comparable countries.

Canadian Institute for Health Information, March 30, 2021

Large numbers of health-care workers likely to quit after COVID-19

Up to 20 per cent of health-care workers are considering leaving their jobs due to the strain of dealing with the COVID-19 pandemic, according to study of staff at a hospital system in the U.S. Those with caregiving responsibilities at home — particularly women — were the most likely to consider leaving or reducing their hours. The results indicate that retaining highly-trained doctors, nurses and scientists could become a major issue after the pandemic.

JAMA Network Open, April 2, 2021

Pregnancy outcomes worsened worldwide

Stillbirth and maternal mortality rates increased by approximately one-third around the world during the pandemic, according to a review of studies from 17 different countries. Mental health outcomes also worsened, with several studies reporting an increase in postnatal depression, maternal anxiety, or both during the pandemic. Overall, outcomes were worse in low- and middle-income countries compared to high-income countries.

The Lancet Global Health, March 31, 2021

Huge jump in excess deaths in 2020 in the US

The number of excess deaths in the U.S. each year — deaths above the number that would be expected based on averages from the previous five years — usually fluctuates by just two per cent. But between March 2020 and January 2021, excess deaths jumped by an incredible 23 per cent across the country. COVID-19 accounted for most of these deaths — 72 per cent — but many of the rest were related to disruptions caused by the pandemic, such as people not seeking or finding adequate care in emergencies like heart attacks, experiencing fatal complications from a chronic disease such as diabetes, or facing a behavioural health crisis that led to suicide or drug overdose. Black Americans were hardest hit, experiencing a higher excess death rate than white or Hispanic people, and a higher excess death rate than their share of the population.

JAMA, April 2, 2021

UK variant was spreading for months before discovery

The highly contagious and lethal B117 variant of SARS-CoV-2 was first identified in December 2020 in the U.K., where it is thought to have originated, but had already been silently spreading around the globe for months. A study looked at data from 15 countries around the world and found that the variant had almost certainly been introduced into all 15 by travellers from the U.K. by mid-November 2020. In the U.S., it likely arrived by mid-October. The study does not include data for when the variant likely arrived in Canada.

Emerging Infectious Diseases, March 24, 2021

T cells can still recognize variants

As new variants of SARS-CoV-2 arise, there is concern that they will be able to evade the protective immune response generated by previous infection or vaccination. Some studies have already shown that the antibodies produced by current vaccines are less able to recognize variant versions of the virus. But a new study has found that another important part of the immune response, the CD8+ T cells that recognize and kill infected cells, remain active against most known variants and so still offer some protection against new versions of the virus.

Open Forum Infectious Diseases, March 30, 2021

High BMI and diabetes are risk factors for infection

While it is known that people with Type 2 diabetes or a high body mass index are at higher risk of hospitalization or severe COVID-19, a new study has found that they are also at higher risk of getting infected in the first place. The study looked at 500,000 people in the U.K. and found that, after controlling for confounding factors like socioeconomic status, age, gender and ethnicity, those who had positive COVID-19 test results were more likely to be obese or have Type 2 diabetes. Those who tested negative were more likely to have high levels of “good” HDL cholesterol and be at a healthy weight with a normal BMI.

PLOS One, April 1, 2021