LONDON – Covid-19 infections among vaccinated people complicate the fight to control the coronavirus. And in the UK, where the path of the disease has been followed more closely than just about anywhere in the world, they are on the rise.
Breakthroughs happen because vaccines, while still providing strong protection against serious illness and death, are not bulletproof. In some cases, the virus can still infect the body and multiply, causing disease, before the immune response can tackle it. Immunity to vaccination also declines over time, prompting many countries, including the UK, to roll out booster-shot campaigns.