Janssen_Novavax Combo
Image Credit: Gulf News

More COVID-19 vaccines are coming. That’s good news since the number of cases has been soaring worldwide. Two new vaccines have caught the attention, having published their Phase 3 results last week.

Johnson & Johnson has developed a single-dose Janssen vaccine, while Novavax’s jab is a two-shot dosage like all other coronavirus vaccines. Johnson & Johnson’s vaccine showed a 78 per cent efficacy rate in US trials, while the Novavax’s recorded 89.3 per cent efficacy in the UK trials.

So what makes these vaccines different from the rest. Yes, Johnson & Johnson’s single jab is a telling difference, but reports say that the company is working on a double-dose vaccine to improve its efficacy.

A one-dose coronavirus vaccine? That could be a gamechanger because more people could be vaccinated. Which means vaccination programmes can be speeded up if the production can keep up. “If it’s a single-dose vaccine, then a billion vaccine doses would translate into a billion people vaccinated,” Dr Dan Barouch of Harvard Medical School in the US told CNN.

The two new vaccines have done what the approved vaccines haven’t. They have proven to work (in trials) against most of the variants in circulation. Johnson & Johnson and Novavax have conducted Phase 3 trials in regions where the newer strains have been found. But significantly, both recorded lower efficacy in South Africa, where the most virulent variant has been found.

What are the vaccines?

Janssen vaccine: Johnson & Johnson’s COVID-19 vaccine, called JNJ-78436735 or Ad26. COV2. S, is developed by collaborating with its Belgium-based vaccine division, Janssen Pharmaceutical, and Beth Israel Deaconess Medical Centre in Boston, US.

Novavax vaccine: This is developed by Novavax, a company based in Maryland, US, and the Coalition for Epidemic Preparedness Innovations (CEPI). The protein-based coronavirus vaccine is called NVX-CoV2373.

How do Janssen and Novavax vaccines work?

Janssen: It’s a viral vector vaccine. That means an adenovirus (which causes the common cold) works like a Trojan horse to carry the genetic material or DNA for the coronavirus spike protein into the human body’s cells. The modified adenovirus can’t replicate or cause an infection. The adenovirus with the coronavirus gene teaches the human body to create antibodies to fight the coronavirus: the gene produces the coronavirus spike protein, and the body responds with antibodies to fight SARS-CoV-2, the new coronavirus.

Novavax: The Novavax vaccine uses a lab-made version of the SARS-CoV-2 spike protein, which is inserted into a virus and allowed to infect moth cells to produce spike proteins. These are harvested and assembled into nanoparticles to make the vaccine formulation. A chemical, called an adjuvant, is added to the mix to stimulate the immune system to respond more strongly to the nanoparticles.

How different are these vaccines from others?

Janssen: Johnson & Johnson’s vaccine is the only single-dose COVID-19 vaccine. Its approach is similar to the mRNA vaccines designed by Pfizer-BioNTech and Moderna. Dr Paul Offit, the director of the Vaccine Education Centre at Children’s Hospital of Philadelphia, told the CNN. But the technology is identical to that of the Oxford University-AstraZeneca vaccine as both use the viral vector route.

Novavax: It works differently from the other vaccines, employing a recombinant nanoparticle technology. It uses protein to provoke an antibody response, and Matrix-M adjuvant enhances the immune response to the protein antigen. The Novavax vaccine can also destroy infected cells, according to a report in the New York Times.

How effective is the vaccine?

Janssen: The single-dose vaccine was found to be 66 per cent effective in preventing moderate and severe disease in a worldwide Phase 3 trial, according to the results announced on January 29. It’s 85 per cent effective in preventing hospitalisation and death, Johnson & Johnson said. In the US trials, the vaccine had an efficacy of 72 per cent, while it was 66 per cent in Latin America (where one of the variants is circulating in Brazil).

Novavax: The United Kingdom trials reported an efficacy rate of 89.3 per cent, according to results announced on January 28. The efficacy against the original COVID-19 strain was calculated to be 95.6 per cent, and it was around 86 per cent effective at protecting against the new UK variant.

Will it work against the South African variant?

Janssen: It is effective, but the efficacy is lower. The results show a 57 per cent success in South Africa, and researchers say the lower rate is likely due to the rise of the B. 1.351 variant. The variant is reported to be more contagious and has mutations, making it less vulnerable to antibodies.

Novavax: In South Africa trials, the efficacy rate was under 50 per cent. This could potentially be the result of B. 1.351 variant that can evade antibodies produced by the body. The company is working on a vaccine that is tailored to the variant.

Image Credit: Seyyed Llata/Gulf News

What’s the dosage?

Janssen: A single dose

Novavax: The vaccine is administered in two doses, one month apart.

What are the potential side effects?

Janssen: The most common reactions after the vaccine was administered included: pain at the injection site, fatigue, headache and muscle aches. But these are consistent with the side effects from other COVID-19 vaccines.

Novavax: No serious adverse events were reported in the trials. Other side effects were mild or absent, according to Novavax.

Who can take these vaccines?

The two vaccines are awaiting authorisation for emergency use, followed by a full approval (if eligible) later. All efforts for most COVID-19 vaccine candidates focus on adult populations. The options for children and teens are expected later in the year.

Do they have to be stored at a freezing temperature?

Unlike the messenger RNA vaccines, these two vaccines do not require freezing temperatures for safe storage.

Janssen: The vaccine can be stored at normal refrigerator temperatures. It is stable for up to three months at 2 degrees centigrade to 46 degrees centigrade, the company said. So health care facilities would not have to buy extra equipment to transport and store the vaccine safely. It will last for two years if kept at minus 20C.

Novavax: The vaccine would be easier to store and distribute as it can stay stable for up to three months in a refrigerator. It has to be transported and stored at 2C to 8C. At those temperatures, the vaccine can last at least six months.

How long will these vaccines protect against COVID-19?

It’s difficult to put a definite timeframe since all the coronavirus vaccines are new.

Dr Peter Marks, the head of the US Food and Drug Authority’s Centre for Biologics Evaluation and Research, said: It appears there’s a duration of protection against disease of at least several months. It’s probably at least on the order of four to six months. Some researchers expect the protection to last for years, but they aren’t certain.

If other protein-based vaccines are any indication, the Novavax vaccine can create memory B cells and memory T cells that retain information about the coronavirus for years to mount an immune response to a new infection.