An Echelon Media Company
Wednesday December 8th, 2021

Sri Lanka pondering COVID-19 booster shot as int’l studies question Chinese jabs

ECONOMYNEXT – Sri Lanka’s Director General of Health Services will issue guidelines for a COVID-19 vaccine booster shot after analysing all available data, a health official said, as international studies questioned the length of protection offered by Chinese vaccines.

Deputy Director General of Health Services Dr Hemantha Herath said recommendations for a third dose have been issued by the Advisory Committee on Communicable Diseases to the Health Ministry, which is now taking relevant measures including the formulation of guidelines for booster administration.

“We need to certify the vaccines consignment that we have yet to receive, and the necessary steps are being taken by the ministry at the moment,” Herath told reporters on Friday (15).

“The Director General of Health Services will issue the guidelines for the booster dose along with who will be prioritised in the rollout and when it will be done,” he said.

Booster dose and additional dose

Online literature shows that booster doses are administered to a vaccinated population that has completed a primary vaccination series (currently one or two doses of COVID-19 vaccine depending on the product) when, with time, the immunity and clinical protection has fallen below a rate deemed sufficient in that population. The objective of a booster dose is to restore vaccine effectiveness from that deemed no longer sufficient.

Additional doses of a vaccine, meanwhile, may be needed as part of an extended primary series for target populations where the immune response rate following the standard primary series is deemed insufficient. The objective of an additional dose in the primary series is to optimise or enhance the immune response to establish a sufficient level of effectiveness against disease. In particular, immunocompromised individuals often fail to mount a protective immune response after a standard primary series, but also older adults may respond poorly to a standard primary series, according to online reports.

Who needs a third dose

The Strategic Advisory Group of Experts (SAGE) of the World Health Organisation (WHO) has said for the Sinovac and Sinopharm inactivated vaccines, an additional (third) dose of the homologous vaccine should be offered to persons aged 60 and above as part of an extended primary series, international media reported this week.

The use of a heterologous platforms vaccine for the additional dose may also be considered based on vaccine supply and access considerations.

SAGE said when implementing this recommendation, countries should initially aim at maximising 2-dose coverage in that population, and thereafter administer the third dose, starting in the oldest age groups.

“Those people who have serious immunocompromised conditions that don’t seem to respond to the first two doses in the way that people who don’t have an immunocompromised condition do, what they need is they need a third dose, but that’s really for their primary response.” Katherine O’Brien director of the W.H.O.’s department of immunization, vaccines and biologicals was quoted as saying.

“It’s because they haven’t adequately responded to the first two doses. But apart from the protection that a booster dose affords people, there are some other considerations we need to know.”

However, O’Brien said current evidence does not show a need to give a booster dose for the majority of a community.

“The evidence is weak for making that argument. We certainly don’t see conclusive evidence that a booster dose among the majority of people who have been vaccinated already is needed,” O’Brien said.

“Giving a third dose needs to be monitored for safety issues, and we would like to see a safety database before we would make any such recommendation. And that evidence is also building, but we’re not there yet.”

O’Brien said current evidence shows that the vaccines that people have received are holding up really well to protect them against severe disease, against hospitalisation and against death.

Concerns over efficacy of China manufactured vaccines

British scientific journal Nature on October 14 reported that scientists around the world have started to question the protection offered by the China manufactured vaccines.

The journal quoting Manoel Barral-Netto, an immunologist at the Oswaldo Cruz Foundation in Salvador, Brazil said the recommendation of an additional (third) dose of the homologous vaccine should be offered to persons aged 60 and above by the WHO is “sensible and necessary” with studies suggesting that the immunity from two doses of either vaccine wanes rapidly, and the protection offered to older people is limited.

Both Sinovac and Sinopharm are inactivated vaccines. Quoting researchers, Nature said this type of vaccine seems to be less potent because it triggers an immune response against many viral proteins. By contrast, mRNA and viral-vector vaccines target the response to the spike protein, which is what the virus uses to enter human cells.

Sinopharm is the most widely used vaccine in Sri Lanka, with 11,834,121 people getting the first dose and 9,981,562 getting two doses so far.

Nature said, some studies have found that compared with vaccines made using other technologies, China’s inactivated vaccines initially generate lower levels of ‘neutralising’ or virus-blocking antibodies — considered a proxy for protection — and that these levels drop quickly over time.

The Sri Lanka Medical Association (SLMA) has recommended administering Pfizer-BioNTech, Moderna or AstraZeneca as the third dose for people over 60.

Citing research conducted in the Middle East, an SLMA statement said the Chinese Sinopharm vaccine is shown to be less effective in the over-60 population category.

The medical body has made a set of recommendations for Sri Lanka’s vaccine rollout, after analysing international data.

“Researches done in Bahrain and Middle Eastern countries using four types of vaccines, Sinopharm, Pfizer, Sputnik V and AstraZeneca, have shown that the fatality rate and severe case rates have gone down due to vaccination,” consultant Immunologist and head of the department of Immunology at the Medical Research Institute Sri Lanka Rajeev De Silva said in an earlier report.

“However, from the deaths that occurred even after being completely vaccinated, most had been given the Sinopharm vaccine,” he said.

Silva said, quoting a study done by the University of Sri Jayewardenepura, around seven percent of the above 60 populations that get Sinopharm did not produce any antibody in them.

Silva said taking the unresponsive number into consideration and after analysing the data, the SLMA has recommended that a third dose be administered to those above 60 years of age who had received Sinopharm, and that this third dose be AstraZeneca, Pfizer or Moderna.

“The third dose should be given one month after giving the second dose,” Silva said.

According to the State Pharmaceutical Corporation (SPC) Chairman, Sri Lanka has placed an order for 14 million doses of the Pfizer-BioNTech COVID-19 jab to vaccinate people under 20 and as a booster shot.

“This is new disease; the vaccines are new. And all these things are still being studied by the authorities” Dr Herath said.

“And in the future according to the data we receive we can take a decision, whether there will be an annual dose, or we can end it with a booster dose.”

Herath said vaccination will minimise the contraction of the virus, and ask the general public to continue to follow health guidelines. (Colombo/Oct15/2021)


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