Until now, it has been unclear what effects hypervaccination such as this would have on the immune system. Some scientists were of the opinion that immune cells would become less effective after becoming used to the antigens.
A team of experts has, in fact, tracked the enzyme in Britain, India, Pakistan and Bangladesh and believes it to be more widespread than first thought. It is said to be resistant even to a class of antibiotics known as carbapenems, which are reserved for use in emergencies and used when bacteria are found to be resistant to more commonly prescribed antibiotics.
The decline in the effectiveness of Covaxin, India's indigenous COVID-19 vaccine, from 77.8 per cent to 50 per cent during a Delta-driven case surge in April and May this year is neither bad nor surprising, say scientists.
The vaccination drive was only one important part of India's globally recognised pandemic management and response strategy, observes Dr Vinod K Paul.
The researchers from King's College London in the United Kingdom also found that most systemic side effects -- meaning side effects excluding where the injection took place -- peaked within the first 24 hours following vaccination and usually lasted 1-2 days.
Results of an interim study recently published in The Lancet showed that two doses of Covaxin, also known as BBV152, had 77.8 per cent efficacy against symptomatic disease and present no serious safety concerns.
According to the findings of the phase 1/2 randomised clinical trial, published in The Lancet Infectious Diseases journal, the vaccine candidate could induce an antibody response in participants within 28 days of the first immunisation, by giving two doses 14 days apart.
More than 100 medical experts, academia and scientists on Friday have called for the Rio Olympic Games to be postponed or moved because of fears that the event could speed up the spread of the Zika virus around the world. Their assessment counters the view of some leading experts of infectious disease who say that as long as the necessary precautions are taken there is no reason to cancel the Games. On Thursday, Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, declared there was no public health reason to cancel or delay this summer's Games. In a public letter posted online, the group of 150 leading public health experts, many of them bioethicists, said the risk of infection from the Zika virus is too high. The letter was sent to Dr. Margaret Chan, director-general of the World Health Organization, and urged that the Games, due to be held in Rio de Janeiro in August, be moved to another location or delayed.
High travel volumes from the disease affected areas in the America, presence of mosquitoes capable of transmitting the virus and limited health resources can lead to Zika virus.
'There is more likelihood of dying from lightning than from vaccine induced blood clots.'
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