PFIZER AND BIONTECH VACCINE TO COMBAT COVID-19

What is in the vaccine?
the Pfizer-BioNTech vaccine is based on the virus’s genetic instructions for building the spike protein. The technology relies on a small piece of messenger RNA (mRNA) from the coronavirus genome. It delivers a gene that codes for the coronavirus' spike protein.

This spike protein is one of four that make up the coronavirus; it helps the virus attach to and invade cells.

A person infected with the coronavirus develops antibodies that neutralize this spike protein. So, RNA vaccines spur the body to produce that spike protein internally. The mRNA enters cells encased in a lipid molecule, then sends a coded message to the body to make the spike protein. That in turn triggers an immune response.

How effective is the vaccine?
About 95 per cent. The phase 3 trials of the Pfizer/BioNTech vaccine involved 42,000 people, about half of whom got the experimental vaccine and the rest a placebo. In total, 170 people fell ill with covid-19.

Only eight of them were in the vaccine group; 162 had received the placebo. So around 5 per cent of cases were in the vaccine group, which is where the 95 per cent figure comes from.

That is a very healthy number: The World Health Organization (WHO) has said it would be happy with 50 per cent.

How long does the immune memory last?
It’s hard to say at this point, because the clinical trials weren’t set up to answer that question, and in any case, they only began dispensing second doses of the vaccine four months ago.

The WHO says that a minimum of six months would be acceptable. It will become clearer as time marches on and the volunteers continue to be monitored.

The Pfizer-BioNTech vaccine requires two injections, given 21 days apart, to prime the immune system well enough to fight off the coronavirus. But because the vaccine is so new, researchers don’t know how long its protection might last.

It’s possible that in the months after vaccination, the number of antibodies and killer T-cells will drop. But the immune system also contains special cells called memory B-cells and memory T-cells that might retain information about the coronavirus for years or even decades.

How long does it take for immunity to develop fully after vaccination?
The trial began assessing immunity seven days after the second shot. We know that protective immunity builds up within four weeks of the first dose, but it appears to develop earlier than that.

How will it be distributed?

At present, BioNTech’s vaccine must be stored at approximately minus 75 degrees Celsius while being transported, making it difficult to deliver to developing countries without robust logistics infrastructure.

The vast majority of doses available in the next year, however, have already been bought by the US, EU and Japan, where shipping hypercold products is far easier. Once it arrives in clinics, the vaccine — which can be kept at approximately minus 75C for up to six months — can survive in a normal fridge for up to 5 days.

To assure product quality, the companies have developed specially designed, temperature-controlled shippers for the BNT162b2 vaccine candidate, which can maintain recommended storage conditions (-70°C ±10°C) for extended periods of time without any additional equipment but dry ice.

The shipper can maintain temperature for 10 days unopened which allows for transportation to markets globally. Once open, a vaccination center may use the specially designed shippers as a temporary storage solution to maintain the recommended storage conditions (-70°C ±10°C) up to 30 days with re-icing every five days in accordance with the handling instructions.

Each shipper contains a GPS-enabled thermal sensor to track the location and temperature of each vaccine shipment 24 hours a day, seven days a week. Once thawed, the vaccine vial can be stored for up to five days at refrigerated (2-8°C) conditions.

What happens to the mRNA in the body?
It is active for a few days then decays rapidly.