Covid 19 Delta outbreak: What you need to know about kids and vaccines

As New Zealand nears the toughest part of its Covid-19 vaccination drive, it's been suggested the Pfizer shot could be offered to children younger than 12 by the end of the year. University of Auckland epidemiologist and data scientist Dr Janine Paynter discusses what that means.

Where are trials currently at with Covid-19 vaccines and children under 12, and what's the evidence telling us so far?

Already, there's an early subset of results available for trials that have been investigating the safety and effectiveness of the Cominarty or Pfizer vaccine for children in different age groups. Around 4500 children aged between six months and 11 years have been participating in them - but only the results for 2268 children, aged five to 11 years, are available at this stage. These are children from the United States, Finland, Poland and Spain. So far, the trial shows that Cominarty is safe and effective for five-to-11-year-olds, and these results are comparable with results for older children and young adults.

Assuming the vaccine is soon approved for use in New Zealand for kids under 12, how will we know it's safe?

Medsafe will carefully review the trial results before it's available to kids under 12 here in New Zealand. It's important to stress that the results will need to meet the same stringent criteria for safety that the vaccine has already met for older age groups.

Could children be more at risk of adverse events from the vaccine?

The children aged five to 11 years have been given a smaller dose of the vaccine than the rest of us. This is because their immune systems are so effective that they need less to make just as good a response - and also, a lower dose is associated with fewer reactions. At this stage, there's no evidence that they're at a high risk of any concerning adverse reactions.

What are we learning about Covid-19 infections and children? With Delta, are they more at risk than they were?

Children are definitely at risk of developing more severe illnesses and ghastly outcomes from an infection with Sars-CoV-2, the virus that causes Covid-19. There's limited evidence to suggest that the Delta variant is worse for children. However, more children are getting infected than we've seen previously, because Delta is more transmissible. The US Centers for Disease Control and Prevention (CDC) has carefully examined the risk of severe illness and death due to Covid-19 in older children – that's boys aged 12 to 17 – compared to the risk of receiving myocarditis, an inflammation of the heart muscle, from the vaccine. They found that, if there were one million boys vaccinated, there would be 215 hospital admissions, 71 intensive care unit admissions and two deaths prevented - and about 56 to 69 cases of myocarditis.

What difference could adding younger children to our vaccine coverage pool make to community protection?

The majority of Covid-19 transmission still occurs within households. However, with Delta, there has been increasing number of documented cases of transmission through schools. Given the potential for serious outcomes in children, combined with this being a transmission pathway, it could be an important key to avoiding ongoing lockdowns and restrictions on gathering sizes.