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SINGAPORE: Early data this week from trials of three possible COVID-19 vaccines have raised hopes of a vaccine being rolled out as early as year’s end.
This is smart news for billions of others by ending a global pandemic that has inflamed more than 14 million other people and killed some 610,000 people worldwide.
But scientists have cautioned against raising expectations because these trials still require much larger studies to prove they can safely prevent infection or serious disease.
HOW DO VACCINES WORK?
Vaccines generally aim to boost the body’s immune system. For COVID-19, 23 vaccines are on human trial. These include inactivated vaccines which are made using particles of the virus that were killed so that they would not be able to infect or replicate in those injected with it.
Doses are also intended for the frame to create antibodies opposed to the dead virus. Chinese corporate staff Sinovac Biotech are among those looking for this type of vaccine.
A new class of vaccine that uses genetic material in the form of ribonucleic acid (RNA) is also being explored, particularly by American company Moderna. The vaccine uses messenger RNA to produce viral proteins that mimic the outer surface of the coronavirus.
The body recognises these virus-like proteins as foreign invaders and can then mount an immune response against the actual virus. Moderna announced promising results on Jul 14 and said it would enter the final stage of human trials on Jul 27.
WHAT HAPPENS IN EACH PHASE OF CLINICAL TRIAL?
Producing a vaccine is a process that involves multiple stages. These include pre-clinical tests which sometimes involve testing on animals to determine if the vaccine produces a desired immune response.
Next comes Phase 1, which is when scientists assess the initial safety of the drug in a relatively small number of people.
Phase 2 judges the vaccine’s efficacy on the virus. Scientists would give the vaccine to a bigger group of people, usually in their hundreds and split into groups, to see if the vaccine acts differently in them. This stage is also used to further test the safety of the trial vaccine.
In Phase 3, the vaccine is introduced to thousands of participants and their blood is compared against to those who receive a placebo.
WHEN CAN WE GET A VACCINE?
More than 140 vaccines are being tested, and 23 vaccine applicants are being tested in humans, according to WHO on 15 July.
Two are in the final Phase 3 trials while one more will begin the final stretch later this month. China’s state-owned Assets Supervision and Administration Commission said a Chinese-made vaccine could be ready as early as the end of this year.
The World Health Organization said in June that a few hundred million doses of the COVID-19 vaccine could be produced until the end of the year, aimed at the people most vulnerable to the virus.
“If we’re very lucky, there will be one or two successful applicants by the end of this year,” SOumya Swaminathan, WHO’s leading scientist, said at a virtual press conference.
Currently, several potential vaccines are in Phase 3 of development. A vaccine being developed by the British-Swedish company AstraZeneca and Oxford University is among them.
Data released on Jul 20 showed it induced an immune response in all study participants who received two doses without any serious side effects. Reports suggest emergency vaccines may be delivered by October. CanSinoBiologics from China and the country’s military research unit have also produced promising results. Researchers said their trial vaccine showed it appears to be safe and induced an immune response in most of the 508 healthy volunteers who got one dose of the vaccine.
About 77 per cent of study volunteers experienced side effects like fever or injection site pain, but none considered to be serious.
Vaccines take several years, if not decades, to be produced, because several sets of tests are required before they can be approved for human use. Given the scale of the existing fitness crisis, scientists are quick to oppose the clock to produce a vaccine in a matter of months.
However, they must demonstrate that they are effective in trials involving thousands of subjects prior to final approval of their use. Given the time and resources required, it is not unexpected that the progression of the vaccine is an expensive business.
Which countries are involved?
Dozens of countries are on the project, adding the United States, the United Kingdom, China and Singapore.
More than 75 countries have also expressed interest in joining the COVAX financing scheme designed to guarantee fast and equitable access to COVID-19 vaccines, the GAVI vaccines alliance said on Jul 15.
“The 75 countries, which will fund vaccines from public budgets, will marry the poorest countries with the support of voluntary donations to GAVI’s COVAX Advanced Market Commitment (AMC),” the alliance said in a statement.
Many of these efforts are transnational in nature. For example, the AstraZeneca vaccine is recently undergoing a Phase 2/3 trial in England, as are Phase 3 trials in Brazil and South Africa.
Sinopharm, administered by the state of China, introduced Phase 3 tests in July in the United Arab Emirates, and another 15,000 people are expected to participate.
HOW LONG DID IT TAKE TO DEVELOP OTHER VACCINES?
Here’s a look at how long it took to expand vaccines for certain infectious diseases.
POULET POX: Also known as the number one chickenpox infection, it was not highlighted by herpes zoster (zone) until the 1950s, and the first vaccine was developed in Japan in the 1970s.
JAUNE FIEBRE: This disease has been present in humans for more than 500 years, and a vaccine was despite everything created in 1937 through Nobel laureate Max Theiler, which is accustomed to this day.
INFLUENZA: During the 1918 influenza pandemic, no cure for the virus was known and the first vaccine did not appear until 1945.
However, just two years later, the researchers concluded that seasonal adjustments in the composition of the virus made existing vaccines ineffective. They found that two main types of influenza viruses are produced, as well as several new strains a year. For this reason, scientists have had to adjust vaccines for both one and both years.
SARS: The virus first infected humans in China’s Guangdong province in 2002 and was identified in 2003 as an animal virus from possibly bats, before spreading to other animals and then humans.
Two SARS vaccines were evaluated in humans, said Professor Kanta Subbarao from the University of Melbourne.
“A number of promising candidates were tested in pre-clinical studies, but they weren’t pursued because SARS didn’t re-emerge,” she said.
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