The following is a summary of some recent studies on Covid-19. They include research that warrants further study to corroborate the findings and that has yet to be certified by peer review.
Unvaccinated children have higher long Covid-19 risk
A small study is adding to evidence that children can develop long Covid-19 even if the virus did not make them seriously ill.
Researchers in Texas who tracked 1,813 children infected with the virus between Oct 2020 and May 2022 – during the waves of the Delta and Omicron Covid-19 variants – found that 4.5 per cent had symptoms for up to 12 weeks and 3.3 per cent had symptoms for longer than 12 weeks.
The risk for persistent symptoms – loss of taste and smell, cough and difficulty breathing – was highest in children sick enough from Covid-19 to be hospitalised.
But 93 per cent of those with long Covid-19 had reported only mild to moderate illness when initially infected, according to the study published in The Pediatric Infectious Disease Journal.
The risk was highest for children infected earlier in the pandemic, before vaccines were available, the researchers said.
Most of the children with long Covid-19 had not been vaccinated, they found.
"There may be a perception that one needs to be hospitalised to have long Covid-19, and that is not what we found.
"I encourage parents to still take caution and get their child vaccinated against Covid-19, because we now know that it will decrease the risk of infection and long Covid," study leader Sarah Messiah of the University of Texas said in a news release.
Experimental at-home test measures Covid-19 antibody levels
An experimental test for at-home use that measures a person's antibody levels to the virus that causes Covid-19 could someday help people know how protected they are against infection and what kinds of precautions they need to take, according to researchers.
Their device – now in the prototype stage – employs the same technology as most rapid antigen tests for Covid-19, except it uses a drop of blood rather than nasal swabs.
As reported in the journal Cell Reports Methods, the test measures the amount of antibodies that are capable of blocking the virus from attaching itself to cells and infecting them.
A smartphone app would then interpret the findings and quantify the person's antibody level.
The test is designed so that the manufacturer could adjust it to account for future variants of the virus, the researchers said.
"Many people probably want to know how well protected they are," study leader Dr. Hojun Li of the Massachusetts Institute of Technology said in a news release.
"But I think where this test might make the biggest difference is for anybody...who doesn't mount good immune responses," such as cancer patients or people taking immunosuppressive medications.
Li's team has filed for a patent but said more research is needed to demonstrate that the test is safe and accurate.
Vision, hearing problems may impede Covid-19 vaccine access
Covid-19 vaccination rates may be lagging among adults with vision or hearing disabilities, US Census Bureau survey data indicated.
Between April 2021 and March 2022, the bureau surveyed 916,085 people about their receipt of Covid-19 vaccines and other healthcare factors.
Overall, 3.8 per cent reported vision difficulties and 2.5 per cent reported hearing impairment.
Researchers found that 83 per cent of people without hearing or vision problems reported receiving at least one dose of a vaccine, compared to 80.7 per cent of those with any hearing impairment and 76.7 per cent of those reporting any vision difficulties, according to a study in the journal JAMA Ophthalmology.
The disparities were more pronounced with more severe impairment, with vaccination rates of 62.9 per cent among those who said they are completely blind and 65.2 per cent in those who are deaf.
"Few state vaccination plans have prioritised adults with vision or hearing disabilities," the authors said.
They called for research on factors that may be contributing to vaccination difficulties for these groups, such as lack of accessible vaccine registration sites and broadcast information for those with vision or hearing disabilities.