While the Health Ministry has been given a fresh start ahead of the New Year with a new leader at its helm, concerns over the efficacy of preordered COVID-19 vaccines and the discovery of a more infectious strain of the coronavirus have put Indonesia’s vaccination plan in the spotlight again.

The country has secured 125.5 million doses of Chinese firm Sinovac’s CoronaVac vaccine candidate despite the lack of efficacy data from the company or the late-stage trials being conducted in Bandung, West Java.

Efficacy, in the case of vaccine development, is the level of effectiveness that a potential vaccine shows in a controlled laboratory environment.

Last week, a Brazilian health authority said that trials of the selfsame vaccine in the South American country showed an efficacy reading between 50 and 90 percent, Reuters reported. As many as 13,000 participants were involved.

The revelation came shortly after researchers in Brazil said just a few days prior that the efficacy of Sinovac’s vaccine was over 50 percent, even though they stopped short of disclosing full results at the company’s request, prompting transparency concerns. The full dataset from the Brazil trials is expected to be revealed on Jan. 7.

Reuters also reported that Turkish researchers found that CoronaVac’s efficacy was as high as 91.25 percent days after their interim trial results were revealed, based on data from 1,322 of the 7,000 participants.

Interim data from the trials carried out in Indonesia is expected sometime in January, but experts have urged authorities to take into account efficacy results from larger trials in other countries, given the relatively small number of Indonesian participants in total: 1,620 people.

Read also: Sinovac vaccine compatible with certain comorbidities: PAPDI

Grading the nation

The government has set a vaccine’s minimum efficacy rate for emergency use at 50 percent, but experts said they would prefer levels of 70 percent or more. This is because the number also determines how many people in the country would need to be inoculated in order to reach herd immunity, should that be the state’s main goal.

Herd immunity means getting a large number of people to develop immunity to stop the virus from spreading to the entire population. It can be used to protect people who are not able to get vaccinated.

President Joko "Jokowi" Widodo said on Dec. 18 that the government aims to vaccinate up to 70 percent of the entire population, or roughly 182 million people, in order to reach herd immunity.

This number signifies the total number of people aged 18 years and over and excludes people with comorbidities, recently infected people and some pregnant women, which Health Minister Budi Gunadi Sadikin explained in detail on Tuesday. People over 59 could also be included once trial data shows that it is safe enough for them.

This estimate is already higher than the vaccination plan revealed by former health minister Terawan Agus Putranto earlier this month, which set out an immunization drive for up to 107 million people aged 18-59 years, roughly 40 percent of the total population.

But the required coverage depends largely on a vaccine’s efficacy and its reproduction number (R0), which is the figure denoting how infectious it could be. The lower the efficacy rate, the wider the coverage required to reach herd immunity. The higher R0 is, the more people would need to be inoculated, and this number usually varies between regions.

"It's difficult to get a valid reproduction number in Indonesia. The very high positivity rate makes it harder to believe in regions claiming their reproduction number is at 1," Griffith University global health researcher Dicky Budiman told The Jakarta Post recently.

Diversifying options

Indonesia's positivity rate, that is the share of tests that comes back positive, is above 20 percent, higher than many other countries and at least four times the ideal rate of below 5 percent. Dicky took it as a sign that the nation’s infection rate was high and its testing capacity was low.

Read also: Without govt support, COVID-19 testing remains low in Indonesia

Assuming the reproduction number is 2, as used in global studies, and vaccine efficacy at 50 percent, the country would need to vaccinate its entire population, Dicky said, which was plainly impossible because of people who cannot get vaccinated for various reasons.

If vaccine efficacy was at 60 percent, Dicky said 83 percent of the population would need to be inoculated, which is still doable but with challenges. If the government aimed to vaccinate only around 60 to 70 percent of its population, then it would need vaccine candidates with an efficacy rate above 70 percent, he said.

"But if the reproduction number in a region is high, there must be vaccine diversification. We could use vaccines with 60 percent efficacy but the largest share should go for vaccines with efficacy above 80 percent, so that it'll reduce the burden in meeting the required coverage," he said.

There is already a formula to estimate the necessary coverage, but given that SARS-CoV-2 is just emerging, the numbers used in the equation – efficacy and reproduction number – are “uncertain and may vary according to context", Harvard University epidemiologist Marc Lipsitch wrote for the Center for Communicable Disease Dynamics. The calculation, he suggested, may be too simple and overly optimistic.

The Health Ministry's spokesperson on COVID-19 affairs, Siti Nadia Tarmizi, acknowledged in an interview with the Post on Saturday that lower efficacy rates would require wider coverage but said that "70 percent [coverage] is sufficient if efficacy is at 60 to 80 percent".

Availability and hesitation

The challenges that Indonesia faces will have much to do with vaccine availability, with the country only having managed to secure firm orders of around 175 million doses, mainly from Sinovac and US firm Novavax.

Minister Budi said the government was finalizing deals for additional supplies with Pfizer and AstraZeneca, whose vaccine candidates have reported efficacy rates of over 90 percent and 70 percent, respectively. He said Indonesia would need 426.8 million doses for those targeted in the vaccination campaign, including wastage.

In addition to that, recent surveys have shown the majority of the people are hesitant about getting vaccinated.

The government has made the vaccines free of charge, and task force spokesman Wiku Adisasmita said regional administrations were allowed to punish people who refused to be inoculated.

Such measures may be taken if they are “effective in correcting public [sentiment] in order to get vaccinated and easily develop herd immunity”. Experts have lamented this decision for failing to adhere to the basic principles of free and voluntary vaccination.

Another concern was the effect of a new virus variant found in the United Kingdom, which is believed to be up to 70 percent more transmissible, on vaccines currently in use and in development.

Read also: Indonesia bans entry of foreigners to curb spread of coronavirus

While experts are still studying the effects of this virus strain, it is believed that the new variant will not affect the effectiveness of current vaccines.

Research and Technology Minister Bambang Brodjonegoro said Thursday that current evidence did not point to the new variant's impacts on vaccination, nor on its effects on the severity and morbidity of the disease.

It would, however, require some adjustment in polymerase chain reaction (PCR) testing, as it affects one of the three genomic targets used in some tests to detect the virus.

However, he did not dismiss the possibility that vaccines could require adjustment, as was the case with flu shots.

Indonesia has not detected the new variant within its borders, unlike neighboring Singapore, but this might as well be because the country still needs to improve its genomic and molecular surveillance and monitoring by way of genome sequencing.

"We've carried out whole genome sequencing, but it appears that we need to routinely intensify whole genome sequencing against SARS-CoV-2. Most importantly, [we must] also share data among countries and institutions running whole genome sequencing," Bambang said.

Editor's Note: Updated to include details from the government's latest vaccination plan.