By Ajita Rijal Kathmandu, Feb. 24: The government has decided to provide the second dose of Covishield vaccine only after eight to 12 weeks of the first phase of vaccination – at least four weeks behind the schedule. The Ministry of Health and Population (MoHP) changed the schedule following the decision of the Vaccine Advisory Committee. The advisory committee advised the government to reschedule following recommendations from the World Health Organisation’s Strategic Advisory Group of Experts on Immunisation to maintain an interval of eight to 12 weeks between the first and second dose of the Covishield vaccine, which is developed by the University of Oxford and pharmaceutical giant AstraZeneca, and produced by the Serum Institute of India. “In light of recent observations, the two-dose efficacy and immunogenicity is said to increases with a longer interdose interval. If the second dose is inadvertently administered less than four weeks after the first, the dose does not need to be repeated," informed the WHO’s Strategic Advisory Group of Experts on Immunisation (SAGE). “If the duration between the first and the second dose is longer, the vaccine will prove to be more effective. So we recommend eight - 12 weeks interval between the first and second doses,” said Dr. Shyam Raj Upreti, coordinator of the COVID-19 Vaccine Advisory Committee at the MoHP. The efficacy of the vaccine was found to be 81.3 per cent with a longer interval of 12 weeks between the first and second dose, compared to 55.1 per cent efficacy in case of a six-week gap, according to the Lancet study. “Various studies and research have found that a four to 12 weeks interval to be the most optimal balance,” said Dr. Rabindra Pandey, a public health expert. However, it is advised to get the second dose of Covishield after 8 weeks, added Dr. Pandey. The government rolled out its coronavirus vaccination drive on January 27. In the first phase of the campaign, front line workers including health workers, staff of the health facilities, female community health volunteers, ambulance drivers, security personnel deployed for management of bodies of the dead, as well as senior citizens living in old-age homes and prisoners got the jab. Soon after, Media Personnel, employees of UN agencies and dependents of foreign employees and employees of embassies and diplomatic missions, government offices and local representative followed suit. The MoHP is preparing for the second phase of the vaccination drive at the community level from March 7. People above 55 years of age are on the first priority list in that phase.