Jan 27 (Reuters) – 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.

mRNA vaccines safe during in vitro fertilization

COVID-19 vaccines using mRNA technology do not affect fertility outcomes during in-vitro fertilization (IVF), researchers have found.

They compared rates of fertilization, pregnancy, and early miscarriage in IVF patients who had received two doses of the vaccines from Pfizer (PFE.N) with BioNTech or Moderna O> with those in unvaccinated patients. The 222 vaccinated and 983 unvaccinated patients who underwent ovarian stimulation – medical treatment to stimulate development of eggs – had similar rates of eggs retrieved, fertilization, and embryos with normal numbers of chromosomes. The 214 vaccinated and 733 unvaccinated patients who underwent frozen-thawed embryo transfer – where their eggs were collected from the ovaries and fertilized by sperm in a laboratory, creating embryos that were frozen and later thawed and transferred to the womb – had similar rates of pregnancy and early pregnancy loss, according to a report published on Tuesday in Obstetrics & Gynecology.

“Our findings contribute to the growing body of evidence regarding the safety of COVID-19 vaccination in women who are trying to conceive,” the researchers concluded.

Healthy gut bacteria may protect during COVID

The bacteria living in your small intestine may contribute to the risk for long COVID after infection with SARS-CoV-2, new findings suggest.

Researchers analyzed the “gut microbiome” in 116 COVID-19 patients in Hong Kong in 2020, when regulations required that every infected person be hospitalized. More than 80% were mildly or moderately ill, but more than 75% had at least one persistent symptom. After six months, the most common symptoms were fatigue (reported by 31%), poor memory (28%), hair loss (22%), anxiety (21%) and sleep disturbances (21%), according to a report published on Tuesday in Gut. Analyses of stool samples obtained at hospital admission and over the succeeding months showed long COVID patients “had a less diverse and less abundant microbiome,” said Siew C. Ng of The Chinese University of Hong Kong. “Patients who didn’t develop long COVID had a gut microbiome similar to that of people without COVID-19.”

Lack of “friendly” immunity-boosting Bifidobacteria species was strongly associated with persistent respiratory symptoms, Ng noted. While the study cannot prove that healthy gut organisms prevent long COVID, the findings suggest “maintaining a healthy and balanced gut microbiota via diet, avoidance of antibiotics if possible, exercise and supplementing with depleted bacteria species including Bifidobacteria” might be helpful, she said.

New PCR test can identify variants

A new type of PCR test can quickly tell which variant of the coronavirus is causing infection, helping doctors choose the most effective antibody treatments, researchers said.

Most current PCR tests can check broadly for the presence of the virus but cannot identify specific variants. The new test uses special “probes” – fluorescently labeled molecules – called “sloppy molecular beacons” that glow in different colors when they attach themselves to DNA or RNA in the virus. When the sample from the patient is heated, the probes fall off their DNA or RNA targets and their color disappears. They fall off at different temperatures depending on the DNA or RNA sequence they were bound to. Because the variants each have some unique sequences, they can be identified based on the pattern of color changes at each temperature, explained Dr. David Alland of Rutgers New Jersey Medical School.

“We have already performed a clinical study which showed that the assay was 100% sensitive and 100% specific for identifying variants of concern including Delta and Omicron,” Alland said. “We are asking the N.J. Dept of Health to clear our test” so that New Jersey labs can use it, he added. A typical hospital molecular laboratory would be able to perform it, his team reported on Friday on medRxiv ahead of peer review.

U.S. study finds slight myocarditis risk with mRNA vaccines

There is a small but increased risk for heart muscle inflammation, or myocarditis, following receipt of the mRNA COVID-19 vaccines from Pfizer/BioNTech and Moderna, researchers from the U.S. Centers for Disease Control and Prevention have found.

The 1,626 cases documented in the Vaccine Adverse Event Reporting System from December 2020 through August 2021 “exceeded the expected rates,” the researchers reported on Tuesday in JAMA. Overall, 73% of reported cases were in people under age 30, and 82% were males. The highest rates were found among adolescent and young adult males. For every million doses of Pfizer’s vaccine, there were roughly 71 cases of myocarditis in males ages 12 to 15 and 106 cases in males ages 16 or 17. In young men ages 18 to 24, the rate per million doses was roughly 52 with the Pfizer shots and 56 after Moderna shots. About 96% of patients with myocarditis were hospitalized. In 87%, symptoms were gone by the time they were discharged. Non-steroidal anti-inflammatory drugs were the most common treatment.

“This risk should be considered within the context of the significant benefits of COVID-19 vaccination in preventing COVID-19 infection and potential serious complications,” said a spokesperson for the authors, who noted that COVID-19 itself confers a 16-times higher risk for myocarditis. “The benefits of COVID-19 vaccination continue to outweigh any potential risks.”