KUALA LUMPUR: Governments must prepare for mutual recognition of Covid-19 vaccination certificates to facilitate quarantine-free travel between countries with low infection rates.
Medical experts said it was necessary as the proposed "immunity passport" for people who have been vaccinated was fraught with challenges.
Epidemiologist Professor Datuk Dr Awang Bulgiba Awang Mahmud said the proposal for a vaccination passport to enable safe travel required plenty of work to realise due to numerous issues, including concerns about sovereignty, the rights of nations, individual rights, as well as questions on the feasibility of establishing such a system and its trustworthiness and effectiveness in the face of potential virus mutations.
He said the variability in vaccine effectiveness and whether all vaccines could be recognised as being equivalent in effectiveness was also an issue.
"Reciprocal recognition of regulatory approvals from different countries will be needed, and this may prove to be a stumbling block.
"Many Covid-19 vaccines have been produced, but some may come from countries with drug regulatory bodies that are not recognised by other countries. So if we are looking towards vaccination passports for safe travel, this will not be easy to agree on.
"The Chinese vaccines have not been administered in western Europe, but some have been administered in many developing countries and even in eastern Europe, like Serbia, which administered the Sinopharm vaccine (from China) and the Sputnik V vaccine (from Russia)," he told the New Sunday Times.
He said this amid discussions on the types and efficacy of Covid-19 vaccines.
For example, Saudi Arabia recognises only the Pfizer-BioNTech and AstraZeneca Covid-19 vaccines, while the European Union is wary of Chinese and Russian vaccines.
Singapore, meanwhile, has authorised only the Pfizer-BioNTech and Moderna vaccines.
Dr Awang Bulgiba said these differences could affect people who have received vaccines when travel passports are introduced.
"China, for example, has said that it will recognise its own vaccines, but not necessarily others.
"As for Malaysia, we have not stated any such position as it is well known that many countries employ a mix of vaccines in their portfolio.
"Country leaders will likely need to agree on a common protocol for this. The Sputnik V vaccine also promises to cause political divide.
"Hungary has given emergency use approval, and France and Germany are considering Sputnik V, but the rest of western Europe are not. This will be a complex issue to resolve."
Asked if people who had been inoculated with Sinovac could get the Pfizer or AstraZeneca vaccines later, he said the United Kingdom's Joint Committee on Vaccinations and Immunisations had in its advisory on Dec 30 last year mentioned that first and second doses of vaccines given in the UK must be of the same type.
Allowing people to get a third dose of vaccine of another type could be an option for countries to consider, he said.
He said an ongoing study called Com-Cov was looking into whether mixing vaccines was advisable, but it was not yet complete.
"Findings from this study will be very useful in helping nations decide whether mixing vaccines will be an option.
"I am not sure of the optimal waiting period for this, but presumably, it will be at least a few weeks."
Manipal University College Malaysia's Professor of Community and Occupational Medicine Dr G. Jayakumar said the different vaccines had different effectiveness.
Depending on the type of vaccine one received, he said an individual might be 65 to 90 per cent protected against a severe Covid-19 infection.
Therefore, he said, countries might have to create mutual agreements with one another on "bubbles" to allow citizens who received different Covid-19 vaccines to travel.
"We need to be cognisant of other limitations on immunity passports.
"They also pose ethical issues and experts feel they can exacerbate existing inequalities and stratify society into the 'immuno-privileged' and 'immuno-deprived'."
Dr Jayakumar said researchers were currently uncertain about how long the vaccine immunity could last, though some early studies indicate that a booster might be needed after a year.
However, he said, taking into consideration the global shortage of vaccines, there was no need for people to get vaccinated again with another brand.
"The understanding of the efficacy of different types of vaccines is less straightforward than it may seem.
"Researchers have reported that the various available vaccines are almost equally effective across a variety of different types of people, gender and ethnic groups.
"However, it is not a magic bullet to ward off Covid-19 infections.
"Preventive measures have to be strictly continued."
Associate Professor Dr Malina Osman, an epidemiologist and biostatistician at Universiti Putra Malaysia, said it would be a step in the right direction if the government allowed people to choose which Covid-19 vaccine to get and let them volunteer for it.
"Yes, this is undoubtedly a wise step.
"It will alleviate concerns, such as for those looking to travel abroad (business personnel, students, pilgrims or travellers).
"From a public health point of view, all vaccines are safe and effective. There's no need to repeat vaccination from other suppliers."