What do the data tell you about how many New Zealanders have or haven’t been infected?
"The true number of people who’ve had Covid-19 is unknown because we only know about cases who get tested and report their result. The proportion of infections that are reported is probably somewhere between 40% and 65%. It’s unlikely to be much less than 40% because at least 40% of all 20-25 year olds have already reported a case. On the other hand the reported infection rate is typically less than 65% of the infection rate in routinely tested cohorts such as border workers. This means it’s likely that at least half of New Zealanders have had Covid-19, although those that haven’t probably still represent a significant minority."
What does this mean for our herd immunity to Covid?
"The lack of an accurate estimate for the true number of infections creates uncertainty about how much immunity there currently is in the population. This makes it harder to estimate the potential size of future waves of Covid-19 or the impact of new variants. The best way to get an accurate picture of the true number of infections would be to systematically test a representative sample of the population on a regular basis. This would provide high-quality ongoing data about the level of Covid-19 in the community and reduce our reliance on self-reported test results."
Read the full article on the Science Media Centre here