Till date, the common perception among the health fraternity was that the protective immunity is usually seen for three to five months, and then starts waning off.
"This is great news as it gives real hope for vaccine developers," Sandeep Nayar, Senior Director and HOD, Chest and Respiratory Disease at BLK Hospital in west Delhi, told IANS.
"We hope that once a vaccine or vaccines are developed, these will provide long-term protection against this dreaded disease," he added.
The researchers of the new study, including Alessandro Sette, a professor at La Jolla Institute for Immunology in the US, measured antibodies, memory B cells, helper T cells and killer T cells, all at the same time from blood samples of Covid-19 recovered patients.
They found that responses to the novel coronavirus, SARS-CoV-2, from all major players in the "adaptive" immune system, which learns to fight specific pathogens, could last for at least eight months after the onset of symptoms from the initial infection.
"Because of the T cell-mediated immunity, the antibodies can produce memory B cells which may provide immunity against Covid-19, particularly in serious cases," said Neha Gupta, Infectious Diseases Specialist at Medanta - The Medicity.
"As we gain more experience with Covid-19 virus recovery and able to monitor antibody levels over a prolonged period of time, we may see that the immunity may stay more than 6 months and, in some case, may extend up to one year," Praveen Gupta, Director and Head, Neurology, Fortis Memorial Research Institute, Gurugram told IANS.
The findings help clarify some Covid-19 concerning data from other labs, which showed a dramatic drop-off of Covid-fighting antibodies in months following the infection, according to new research published in the prestigious journal Science.
According to the researchers, nearly all Covid-19 survivors have the immune cells necessary to fight re-infection.
"The vaccine studies are at the initial stages and so far, have been associated with strong protection. We are hopeful that a similar pattern of responses lasting over time will also emerge for the vaccine-induced responses," said study co-author Daniela Weiskopf.
In India, as the Covid-19 infections currently affect 0.7 per cent of the population and are concentrated in few cities and states, we may not have acquired larger herd immunity from the disease.
"However, noting the fact that Covid-19 has not spread and caused much mortality in our country, it means that we may have better immunity against Covid-19 than many developed countries," said Gupta.