Coronavirus Vaccine:  In an interim report of an early phase clinical trial, the coronavirus vaccine candidate developed by the pharmaceutical giant Pfizer in association with the German biotech company BioNTech has produced a "robust" immune response in healthy adults aged 18-55 years.

What does the study reveal?

The study published in the journal Nature noted BNT162b1 is an RNA vaccine demonstrated an immune response by mimicking the mRNA molecule used by the novel coronavirus SARS-CoV-2 to construct its infectious proteins.

Basically, the vaccine candidate delivered intramuscularly has enabled human cells to produce proteins part of the SARS-CoV-2 receptor-binding domain, against which the immune system is trained to produce antibodies, as per the PTI report.

Such vaccines are typically found to be safe and led to the rapid development of vaccines against SARS-CoV-2, as per the researchers.

It remains one of several RNA vaccine candidates being studied in parallel for selection to advance to a trial of their safety and efficacy.

As per the researchers, the vaccine demonstrated a "robust immune response" in participants, which increased with dose level, and with a second shot.

In the trial, antibodies against SARS-CoV-2 were present 21 days after a single vaccination at all dose levels. Not just this, there was a substantial increase in SARS-CoV-2-neutralising antibodies seven days after the second 10-g or 30-g dose were administered.

It noted that the immune response was much stronger in the 30-g group than in the 10-g group. However, the scientists didn’t notice any major difference in immune response between the 30-g and 100-g groups after one dose, and as participants who received the 100-g dose also experienced greater side effects, they did not receive a second dose.

The good news is that participants' levels of neutralising antibodies were 1.9 to 4.6 times higher than those in patients recovering from SARS-CoV-2 infection.

What has been examined so far in the trial?

In the ongoing phase of the half trial, the researchers have determined the safety, side effects, and safe dose of the vaccine candidate in 45 healthy adults (23 men and 22 non-pregnant women) aged 18-55 years. The participants were randomised to receive 10 micrograms (g), 30 g or 100 g of BNT162b1, or a placebo, the study noted.

On 21st day, the scientist said 10-g and 30-g groups also received a second dose

BNT162b1 have been well-tolerated, although some of them experienced mild to moderate side effects, which increased with dose level, in the seven days following vaccination. This included pain at the injection site, fatigue, headache, fever, and sleep disturbance.

Although this comparison provides a benchmark for evaluating the vaccine-elicited immune response and the vaccine's potential to provide protection, the researchers believe phase 3 trials are needed to determine the efficacy of BNT162b1.

They said the study is also enrolling adults aged 65-85 years, adding that later phases would prioritise the enrolment of more-diverse populations.