Covid-19: Delta infections threaten herd immunity vaccine strategy

Epidemiologists are adjusting their expectations for the future course of pandemic after data from a recent outbreak in Massachusetts US suggest that while vaccination remains highly protective against worst consequences infection, it may not be sufficient on its own to stop spread delta variant. Testing conducted among residents during an Provincetown, popular weekend getaway spot, 3 17 July found 75% those infected were fully vaccinated, state where 69% adults vaccinated.1 Among vaccinated with breakthrough infections, difficulty detecting virus nasal passages, known as cycle threshold value, was almost identical seen unvaccinated. This finding suggests both groups carried equal viral loads and equally likely pass Centers Disease Control Prevention (CDC) warned. The results support claims people playing role summer surge variant …