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.
Vaccines still effective against Delta variant
The Delta variant of COVID-19 has become dominant around the world, but so far vaccines appear to be holding up well against it. A new study has found that a two-dose regimen of the Pfizer-BioNTech shot was 88 per cent effective at preventing symptomatic disease from the Delta variant, compared to 93.7 per cent against the Alpha variant. A two-shot regimen of the AstraZeneca vaccine was 67 per cent effective against the Delta variant, higher than the 60 per cent originally reported, and 74.5 per cent effective against the Alpha variant.
Mixing AstraZeneca with mRNA gives stronger immune response
Having one shot of the AstraZeneca vaccine followed by a second shot of an mRNA vaccine, either Pfizer-BioNTech or Moderna, resulted in a stronger immune response than having two jabs of AstraZeneca, and an equally strong or stronger immune response than two shots of an mRNA vaccine, according to a study in Germany. Mixing vaccines produced a stronger response from both antibodies and T cell immune cells.
1.5 million kids lost a caregiver to COVID-19
More than 1.5 million children around the world lost at least one parent or grandparent who lived with them to COVID-19-related causes during the first 14 months of the pandemic. Researchers say this highlights an urgent and overlooked long-term effect of the pandemic — traumatic experiences, such as the loss of a parent or caregiver, are associated with increases in substance use, mental health conditions and other behavioural and chronic health conditions. The countries with the highest numbers of children who lost primary caregivers included South Africa, Peru, the United States, India, Brazil and Mexico.
Poorer, minority ethnic neighbourhoods still had worse air pollution than rich white ones
One beneficial side effect of the pandemic was a drop in air pollution in many places, as road traffic and other sources of pollution dropped due to lockdowns. Although levels of nitrogen dioxide from traffic fell sharply in most urban areas, that decrease was not large enough to eliminate the racial, ethnic and socioeconomic disparities in exposure to this pollutant. During the shutdown, marginalized minority communities in some U.S. cities experienced nitrogen dioxide levels that were still 50 per cent higher than pre-pandemic levels in the nearby highest-income, majority-white communities.
Risk of transmission on school buses is low
A study of COVID-19 transmission at a school serving Grade 1 through 12 in Virginia found no cases of infection linked to school buses. The buses operated near capacity, with two students in every seat, using a physical distancing minimum of 2.5 feet, universal masking and simple ventilation techniques. There were 39 cases among students on buses over the course of the year, but contact tracing revealed that none were infected on the bus.
Nurses face significant burnout risk during pandemic
Almost half of nurses and other health-care workers had risk factors associated with a higher likelihood of burnout during the early stages of the pandemic. A survey of health-care workers in June and July 2020 found that 44 per cent were at higher risk for burnout, fatigue and patient errors. The survey also identified factors associated with poor well-being, including believing that supplies of PPE were insufficient, feeling that their organization did not understand their emotional support needs during the pandemic and believing that staffing was inadequate to safely care for patients. Factors associated with better well-being included feeling that the organization did understand emotional support needs and believing that staff were being redeployed to areas of critical need.
Number, not sensitivity, of tests matters
To minimize the number of infections in a population, the amount of testing matters more than the sensitivity of the tests that are used. PCR tests are the most accurate way of diagnosing COVID-19, but rapid antigen tests are cheaper and give faster results. A computer simulation found that using only rapid antigen tests could achieve similar outcomes, in terms of total infections, as using only PCR tests — as long as the number of people tested is high enough. This suggests that lower- and middle-income countries might be able to save money and achieve optimal outcomes by concentrating on ramping up testing using less sensitive tests that provide immediate results, rather than favouring PCR.
Second dose of mRNA vaccine safe even after allergic reaction
A study of people who experienced allergic reactions to one of the mRNA vaccines — Pfizer-BioNTech or Moderna — found that all of them who went on to get a second dose tolerated it without any complications. Even those who had experienced dangerous anaphylactic reactions to the first dose had no major problems with the second. Allergic reactions after mRNA COVID-19 vaccinations have been reported to be as high as two per cent, but these findings suggest that it’s safe for most people to receive a second dose of an mRNA vaccine.
Canada should expect a resurgence in respiratory infections in kids
We should expect a resurgence in childhood respiratory infections this fall and winter as COVID-19 precautions are lifted. Cases of respiratory syncytial virus (RSV, the most common cause of respiratory illness in children) have risen sharply in Australia and, more recently, the United States as COVID-19 case counts have waned and pandemic public health measures have been relaxed. During the pandemic, Canada, like other countries, saw very few cases of RSV, with only 239 cases between August 2020 and May 2021, compared with 18,860 cases in the previous year. But that means that most gestational parents and very young infants did not develop immunity over the past year, so children may develop more severe illness this year.