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 to be breaking down defenses of vaccines not made from the supereffective messenger RNA technology, or mRNA. In places like Mongolia and the UAE, high levels of coverage with Chinese shots using the older, less effective inactivated vaccine platform hasn’t stopped a surge in cases. In the Seychelles, five people fully vaccinated with AstraZeneca’s shot have died.