Delta variant prompts countries using AstraZ vaccine to consider boosters

Countries are hoping a booster could bolster protection ahead of the return of colder weather that's optimal for the coronavirus's spread.

Growing concern that Covid-19 vaccines being deployed across much of the developing world aren’t capable of thwarting the delta variant is prompting some countries to look at offering third doses to bolster immunity against more-infectious virus strains.
 

Though definitive evidence is yet to emerge backing the need for so-called “booster” shots, health officials from Thailand to Bahrain and the United Arab Emirates have already decided to offer the extra doses to some people already inoculated with vaccines from Chinese makers Sinovac Biotech Ltd., Sinopharm and from AstraZeneca Plc.

Officials are being motivated by concerns that delta and other variants appear