An infectious disease specialist from Bangalore, India, warned "the virus will fight back" against vaccination efforts and could create "vaccine escape mutants".
Jackson Health System is among the hospitals working closely with the Florida Department of Health to receive COVID-19 vaccines. Many Indians said that parents here might have questioned why these vacccines weren't 100 per cent effective.
That also leads to the "theoretical risk" of antibody enhancement where contracting something a second time can be more severe than the first - such as dengue fever.
The Sinopharm vaccines, as well as another one from CanSino Biologics, were also shown to be safe and triggered immune responses in early and mid-stage trials, according to peer-reviewed papers.
While the early to mid-stage trials were not created to assess the efficacy of the vaccine, known as CoronaVac, researchers said it could provide sufficient protection, based on their experience with other vaccines and data from pre-clinical studies with macaques.
No serious adverse health events related to the vaccine were seen in the participants and older people were found to have fewer side effects (such as fatigue and muscle ache) than younger participants.
Phase 3 testing for the AstraZeneca and Oxford vaccine is underway around the world.
A team of Anvisa inspectors are now in Beijing completing a two-week quarantine period in a hotel before they can visit a Sinovac lab to certify the vaccine for good manufacturing practices required to register it in Brazil, he said.
Although the results indicate the vaccine is likely to be protective, the trial data is now "blinded", meaning even the researchers do not know who has been immunised and who was given a placebo.
Earlier reports had also suggested that as per a draft plan, 70 lakh healthcare workforce from the public and private sector will be administered the COVID-19 vaccine.
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In the past two weeks, USA companies Pfizer/BioNTech and Moderna have announced results of their own phase three trials - which are much larger than phase two and normally include tens of thousands of subjects - that suggested both vaccine candidates were up to 95 per cent effective in preventing Covid-19.