Science - Covid vaccine quest

By: Ralph Cooney

When will Covid-19 end? Scientists are racing to produce safe and effective vaccines by next year. Progress is now accelerating and becoming more focused. There are 36 vaccines in clinical trials on humans, plus 89 pre-clinical vaccines under active investigation, two vaccines approved for early or limited use – but at present no vaccine is yet approved for full use. There are several different approaches to vaccine design. These include:  

Genetic vaccines: These use one or more of the coronavirus’ own genes to provoke an immune response. One genetic vaccine is being developed by bio-technology company Moderna and the US National Institutes of Health, with US Government funding of $US1 billion. Phase 3 started in late July and the final trial will enroll 30,000 healthy people across 89 sites. The US Government has pre-purchased 100 million doses, provided the vaccine is approved.

Viral vector vaccines: These use a virus to deliver coronavirus genes into cells and provoke an immune response. A viral vector vaccine is being developed by AstraZeneca and the University of Oxford with US Government Funding of $US1.2 billion. Early trials confirmed the vaccine is safe. Phase 2 and 3 are underway. If successful, emergency vaccines could be delivered as soon as October 2020.

Governments in vaccine-manufacturing countries will first plan to over-supply the needs of their own citizens. In New Zealand, we do not have a vaccine manufacturing capability and will need to secure millions of approved vaccine doses from one or more manufacturing countries. New Zealand will need to negotiate for some priority in the national and international queues for doses in the intense international market. You may feel this is a weak position, yet in recent years our country has attracted many international friends and admirers. This “soft power” is likely to prove valuable during negotiations.

How long will vaccine immunity last? Parallels with vaccines for other related viruses suggest a safe and effective vaccination may be required once or even twice a year, like influenza. However, this may be optimistic, and will only be known after the successful vaccine clinical trials are complete.

If the vaccines chosen for New Zealand and the wider world are effective in providing year-to-year protection for the global population, then there will be a pathway to returning to some degree of normal life, travel and business. In this journey, humanity must also consider the vaccine needs of poorer countries, refugees and those in war zones. Until a vaccine is available, follow the essential precautions of distancing, hand hygiene and please wear a mask.

How do we know that COVID 19 vaccines will not harm us?

New Covid-19 vaccines are subjected to rigorous clinical trials before being approved.

These include:

Preclinical Testing: The vaccine is given to animals (mice or monkeys) to see if it produces an immune response.

Phase 1 Safety Trials: The vaccine is given to a small number of people to test safety and dosage and to confirm that it stimulates immune response.

Phase 2 Expanded Trials: The vaccine is given to hundreds of people who are split into groups, such as children and the elderly, to see if the vaccine acts differently in each group. These trials also test safety and ability to stimulate the immune system.

Phase 3 Efficacy Trials: The vaccine is given to thousands of people. Researchers wait to see how many become infected compared to volunteers who receive a placebo. These trials determine if the vaccine protects against the virus. These trials are large enough to reveal evidence for rare side effects.

Regulator approval: Regulators in each country review the trial results and decide whether to approve each vaccine or not. During a pandemic, a vaccine may receive emergency use authorisation before getting final approval. Once a vaccine is licensed, researchers continue to monitor people who receive it to make sure it is safe and effective.


Emeritus Professor Ralph Cooney
r.cooney@auckland.ac.nz

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