MANILA (PHILIPPINE DAILY INQUIRER/ASIA NEWS NETWORK) -After several months of the pandemic and disaster after disaster (as I write this, there's no electricity because of Typhoon "Ulysses"), we are increasingly desperate to see some silver lining.

Which is why news that the Covid-19 vaccine being developed by Pfizer and its German partner BioNTech seemed to be more than 90 percent effective was very much welcomed all over the world, based on an ongoing trial involving over 43,538 individuals.

Based on the press release, this means that out of 94 infections, most of them came from those who received a placebo.

To put things into perspective, the US Food and Drug Administration set 50 percent as the threshold for approving a vaccine for emergency use, and the effectiveness (i.e the ability to prevent illness in the real world) of flu vaccines pretty much hover around that threshold.

A 90 per cent efficacy (i.e. the ability to reduce disease incidence in clinical trials) is better than expected - "just extraordinary," in Dr Anthony Fauci's words - and bodes well for the novel technology (i.e the use of mRNA to target respiratory viruses' spike protein) behind Pfizer/BioNTech's vaccine.

President Duterte, who has long made vaccines a centrepiece of his rhetoric (I discussed the perils and promise of his "vaccine messianism" back in September in this column), hailed the news, saying that "Covid is not that scary anymore," promising that the government will finance the vaccination of all Filipinos by next year, starting with the poor.

Newly-appointed "vaccine czar" Carlito Galvez Jr, for his part, has given May to July 2021 as the "best case scenario" for a vaccine rollout in the country.

Despite the promising results from Pfizer and the promises from the government, however, there are challenges that need to be overcome before we can have a vaccine and finally end the pandemic.

In the first place, Pfizer's results need to be scrutinised through a peer review process and further analyses.

While the 90 per cent efficacy is high, this may still change given the small number - 94 - of infections that has served as the basis for this number (the researchers' target is 164), and it is unclear if and how the vaccine will work for the elderly, children, those who have chronic illnesses, and other vulnerable populations.

Beyond efficacy, there is also the question of durability; that is, how long its protective effect lasts, and how many doses are required.

Currently, our understanding is that this vaccine requires two doses - which means that the 1.3 billion doses that Pfizer pledges to manufacture in 2021 will only be good for 650 million individuals.

Speaking of this limited supply, reports indicate that countries like the US, UK, and Japan may have already reserved much of it through advanced purchasing agreements, raising issues of availability, equity, and the need for vaccine manufacturing capacity at the national level.

Particularly for low- and middle-income countries, there is also the logistical challenge of distributing a vaccine that requires ultra-cold storage (minus 70 or minus 80 deg C) - especially in an archipelagic nation such as ours. Indeed, the challenge is not just to acquire the vaccines themselves but the means to store and distribute them.

In this vein, I welcome the government's seven-point roadmap that at least acknowledges some of these challenges.

One challenge the government needs to address, however, relates to cultural barriers to immunisation.

In urban and rural communities alike, I am hearing a growing sense of conspiracy among people who think "pinagkakaperahan ang Covid"-that is, politicians, hospitals, and businesses alike are supposedly making money out of the pandemic.

Then there's also the pre-existing vaccine mistrust owing in part to the dengue vaccine scandal and ongoing social media misinformation (you'll be surprised at the number of local anti-vaxxer groups and pages on Facebook).

We will need to address these barriers through effective and targeted communication, social science insights, community engagement, as well as integrity and transparency throughout the whole vaccine process.

All of the above challenges notwithstanding, the Pfizer/BioNTech vaccine offers hope that vaccines - including the others under development - can truly contribute to the pandemic's end.

However, it is clear that we cannot just wait for these vaccines to come. Much work is required if we are to realise their promise, and given their uncertain timeline, much work is required to control Covid-19 even without them.

The writer is columnist with the paper. The Philippine Daily Inquirer is a member of The Straits Times media partner Asia News Network, an alliance of 24 news media entities.