Study suggests Delta does not cause more severe childhood Covid

Washington - US study underscores vaccine effectiveness against paediatric Covid hospitalisation during Delta variant

US paediatric Covid hospitalisations have surged since Delta became predominant, but a new study that offers a first look at the relevant data suggests that fears the variant causes more severe disease are unfounded.

The paper by the Centers for Disease Control and Prevention also found that between June 20 and July 31, unvaccinated adolescents were more than 10 times more likely to be hospitalised than those who were vaccinated.

The health agency analysed hospital records from across an area covering around 10 per cent of the US population, between March 1, 2020 and August 14, 2021.

This covered the period before the emergence of Delta, the most contagious strain to date, and after it became dominant, from June 20 onwards.

Weekly hospitalisations of children aged 0-17 were at their lowest between June 12 and July 3, at 0.3 per 100,000, before rising to 1.4 per 100,000 in the week ending August 14 — a 4.7-fold increase.

Paediatric hospitalisations reached their all-time peak of 1.5 per 100,000 in the week leading up to January 9, when the US experienced its winter wave that was driven by the Alpha variant.

Consistent with prior research, children aged 12-17 and 0-4 are at higher risk of Covid hospitalisation than those aged 5-11.

After examining 3,116 hospital records from the period before Delta, and comparing them to 164 records during the Delta period, the percentage of children with severe indicators was found to not differ greatly.

Specifically, the percent of hospitalised patients admitted to intensive care was 26.5 pre-Delta and 23.2 post; the per cent placed on ventilators was 6.1 pre-Delta and 9.8 post; and the per cent who died was 0.7 pre-Delta and 1.8 post.

These differences did not rise to the level of statistical significance.

The finding comes with the important caveat that because the number of hospitalisations in the post-Delta period is small, more data will need to accrue for scientists to gain greater confidence about the conclusion.

The study also underscored vaccine effectiveness against paediatric Covid hospitalisation during Delta.

Between June 20 and July 31, among 68 adolescents hospitalised with Covid-19 whose vaccination status was known, 59 were unvaccinated, five were partly vaccinated, and four were fully vaccinated.

This meant the unvaccinated were 10.1 times more likely to be hospitalised compared to vaccinated.

A second study by the CDC examined childhood Covid cases, hospitalisations, and emergency department visits from June to August 2021, and compared them to the levels of community vaccination at the time.

Covid-related paediatric (ages 0-17) emergency department visits and hospitalisations were 3.4 times higher and 3.7 times higher respectively in states that fell in the bottom quartile of overall vaccinated per capita, compared to states in the highest quartile.

The takeaway message is that, while clinical trials for vaccines among those under the age of 12 and subsequent authorisations are awaited, high community rates of vaccination squelch Covid transmission and protect children.

• USA