Last Friday the CECC announced how it determined if someone was infected with COVID the second time: They would need to have caught COVID more than three months ago, test positive for COVID, and have a CT value that''s less than 30. But just who are particularly vulnerable to refinections? According to a European journal, aside from people who had their last dose of vaccine more than 120 days ago and frontline medical staff, people aged 20 to 39 and women are particularly susceptible.

This year, the COVID pandemic erupted in earnest. Many people have been infected with the omicron variant. According to The New England Journal of Medicine, the body’s immunity to reinfection following a bout of COVID with the alpha or delta strain is over 90%, and reinfection rates are low. By contrast, the body’s immunity to COVID after omicron is a mere 56%.

Voice of Chen Xin-mei
Chung Shan Hospital
In terms of the risk of reinfection, if you’ve had alpha, beta, or delta, your body’s own immunity is actually more than 80% to 90%. But with omicron, it’s only about half, maybe around 56%. So in contrast, this is a high-risk group.

Dr. Chen also highlights a recent European study that specifies four groups of people who are particularly prone to reinfections. Aside from frontline medical workers and people who had their last vaccination more than 120 days ago, statistically younger people between 20 and 39, and women have a higher chance of getting reinfected.

Voice of Chen Xin-mei
Chung Shan Hospital
This group of 20 to 39 year-olds actually have relatively mild symptoms when they catch COVID, so of course once it’s over, they might not take as much care or pay attention, and this is actually a high-risk group when it comes to COVID reinfections. According to statistics in a European journal, women are 1.2 times more likely to be reinfected than men. As for the reason? Well, this is just an observational finding; it is a result of collecting statistics.

Dr. Chiang Kuan-yu
Taipei City Hospital Zhongxing branch
In addition to young people, the younger the child, the higher his or her reinfection rate. According to British findings, the lower a child’s age, the worse it gets. This is because young people are full of activity and it’s harder to get kids to abide by public hygiene measures. It may also be that they have more contact with their peers.

Doctors also say children don’t have a strong enough immune system. Coupled with difficulties in getting them to comply with epidemic prevention measures, the probability of a reinfection in children is not low. Moreover, people who’ve had COVID for three months with a CT value less than 30 and do not consistently test negative should also watch out for reinfection.