To achieve herd immunity, Aus should modify the current vax strategy

A new Covid-19 pandemic tracking system revealed Monday that Australia’s current vaccination strategy should prioritize the administration of the Pfizer jab for people between 12 and 40 to achieve herd immunity.

According to Xinhua news agency, the findings were published in The Medical Journal of Australia (MJA) and were based on a new model created by James Cook University (JCU).

To assess the effect of an epidemic under different public health interventions, the model included age-specific mixing, susceptibility, infectiousness, and severity. It also evaluated different vaccination programs such as AstraZeneca and Pfizer, as well as the mixed program.

Professor Emma McBryde, an Epidemiologist at JCU’s Australian Institute of Tropical Health and Medicine, stated that the modeling indicated Australia’s current strategy of first vaccinating vulnerable older age groups was the best strategy to reduce hospitalizations, deaths and years of lost life. However, it is unlikely to achieve herd immunity due to the Delta strain’s uncertain effective reproduction.

McBryde stated that the current plan to vaccine 80% of the adult population (or about 65% of the total population) falls short of herd immunity.

Although there are uncertainties in the forecast, she said that the range of possible people to whom one infected person could transmit the virus is between three and seven.

To achieve herd immunity, at least 85 percent of the population would have to be vaccinated if there is a reproduction rate of 5 according to most estimates.

The team looked at two strategies for vaccine distribution. One focused on the elderly (people over 55) while the other prioritized the most infected (people under 55). Australia should now be delivering Pfizer vaccines to younger people.

“We will not achieve herd immunity at the maximum reproduction number of five without vaccinations being extended to younger ages and combined with other measures. McBryde stated that Australia should prioritize the delivery of Pfizer vaccine between 12-40 years.

As the COVID epidemic has seen more children admitted to hospitals, there has been much discussion about vaccination. The Sydney Children’s Hospital Network supports more than 2,000 children living with Covid-19, including three children currently in intensive care.

McBryde said that if the virus reproduction numbers are three, the current program could achieve herd immunity at 60-70 percent coverage, without having to vaccinate five- to fifteen-year-olds. However, McBryde stated that a seven-effective reproduction number would make it impossible to attain herd immunity without vaccination.