News Scan for Aug 23, 2021

Breakthrough COVID-19 infectivity
Youth perceptions of COVID vaccines
Another Chinese H5N6 avian flu case

Breakthrough COVID-19 may be less infectious

Being fully vaccinated against COVID-19 significantly decreased the probability of virus culture positivity in breakthrough cases versus cases in unvaccinated healthcare workers, according to a study on the non–peer-reviewed research server, medRxiv.

The results, published late last week, showed that 68.6% of 161 COVID-19 breakthrough infections had positive nasopharyngeal swabs compared with 84.9% of infections in unvaccinated patients. Cycle threshold value (Ct value, an inverse proxy for viral load) was similar for the two groups and decreased throughout the first 3 days of illness in breakthrough cases. It did not significantly differ across vaccine type or time since last vaccine administration.

The cohort consisted of 24,706 fully vaccinated healthcare workers and an unspecified number of unvaccinated healthcare workers in two tertiary care hospitals in the Netherlands. Breakthrough cases were identified from April to July 2021, and out of 126 sequenced cases, 90.5% were the Delta variant (B1617.2). Most (91%) of breakthrough cases occurred in those under 50, with a patient mean age of 25.5 years.

"Our study supports the excellent effectiveness of vaccination in preventing severe SARS-CoV-2 related disease, but also demonstrates that vaccinated individuals can still acquire infection and carry infectious virus," write the researchers. "Although symptomatic vaccinated individuals should be tested to further reduce the chance of virus transmission to individuals at risk for severe disease, further studies are needed to assess whether the decreased infectious virus shedding in breakthrough infections also lowers the chance of virus transmission."

The researchers note that their study does not measure vaccine effectiveness. They also add that, due to the high vaccine coverage in healthcare workers, infections prior to vaccination rollout were used as data reference for unvaccinated infections.
Aug 21 medRxiv study


Most youth would consider COVID-19 vaccination, survey says

A US text message survey for ages 14 to 24 found that almost three out of four were interested in getting a COVID-19 vaccine, according to a JAMA Health Forum research letter late last week.

The open-answer survey was sent out Mar 12, and demographics were matched with US national demographics such as age, sex, race, ethnicity, education, and region of the country. The mean age of respondents was 19.3 years. Not every participant answered all five questions, but most (1,074 out of 1,155) answered at least one.

Out of 1,068 respondents, 74.6% said they were interested in getting vaccinated against COVID-19 to protect themselves and return to normal. The largest concern was adverse effects (41.8% of 1,009), but 11.7% were concerned about effectiveness. Almost one-third (32.1%) had no concerns, and 72.8% of 990 respondents said vaccines were safe and/or effective, citing trust in science (20.1%) and data (30.7%). The respondents also said that they looked for easy sign-up processes and close locations.

About 46% said they would continue mitigating behaviors, such as mask use, even after being vaccinated, while 38.9% said they would change their habits after getting vaccinated (eg, they would go out or travel more). Another portion of respondents (6.9%) said their habits would not change after being vaccinated, but their stance was conditional on factors such as waiting for more of their social circle to be vaccinated.
Aug 20 JAMA Health Forum study


China reports yet another H5N6 avian flu infection

China reported yet another H5N6 avian flu infection, its 17th so far this year and 5th this month, part of an ongoing rise in in human cases involving the strain, Hong Kong's Centre for Health Protection (CHP) said today in a statement.

The latest patient is a 55-year-old man from Guangxi in the south. He is a farmer and had contact with poultry before his symptoms began on Aug 17. He was hospitalized the same day, where he is now listed in critical condition. Earlier this month, China reported another case in Guangxi, which involved a woman who had been exposed to poultry in a live-bird market before she became ill.

Since 2014, when the virus was detected in humans for the first time, China has reported 41 cases. H5N6—one of the strains known to infect humans—circulates in poultry, especially in Asia. However, China and Laos are the only nations to report human cases. H5N6 infections are often severe or fatal.
Aug 23 CHP statement

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