COVID-19 vaccine distribution

For a vaccine to be considered safe and effective, it has to pass a series of trials. These trials are conducted in different phases and with various sections of the population. By the time a vaccine reaches phase III of trials, it may involve thousands of people of different ages, stages in life (for example, pregnant women), race and gender, etc.

Recent trials for COVID-19 vaccine candidates are being followed closely by scientists, governments, media and the general public. Already, some trials have been stalled or paused and restarted after volunteers developed health issues.

A recent instance was that of a volunteer developing transverse myelitis which led to the clinical trials of a vaccine being put on hold temporarily. Transverse myelitis starts with swelling around one section of the spine; eventually, the sheaths covering the nerves in this section start getting damaged. (Read more: Oxford-AstraZeneca’s COVID-19 vaccine trial paused after case of illness)

The temporary stoppage of a vaccine trial is done to first find out if a health complication in a volunteer is the result of the vaccine or not—it is important to rule out health conditions (other than some expected issues like fever and pain at the injection site) developing because of the vaccine before giving it to billions of people.

According to the panellists, steps such as stalling the trial show that the process of testing the vaccine is being conducted properly. Complications or side effects—if at all related to the vaccine—must be addressed as and when they are discovered. It is important for the scientific community to be honest and transparent about the efficacy and legitimacy of the trials.

AstraZeneca and Oxford University paused their COVID-19 vaccine trial for less than a week in September 2020. They hit the pause button after a volunteer in the trial who got their adenovirus vector-based vaccine got sick. This hurdle created ripples also because adenoviruses are DNA-based viruses that are often used as a carrier (vector) for vaccines.

Here's why: adenoviruses cause mild illness that is often self-limiting in humans. So the adenoviruses jump-start the immune response initially, but the full force of the immune action is geared towards the deadlier pathogen (in this case, SARS-CoV-2, which causes COVID-19).

As a majority of the vaccines being developed for COVID-19 are based on this particular strategy (adenovirus as a carrier for the vaccine), any adverse event could mean potential re-checks for the many vaccines that are based on this concept to help the immune system fight COVID-19.

Read more: Vector vaccines

If taken in the proper spirit, these impediments could prompt vaccine scientists to take greater care in the development stage and make a course correction early. These issues are par for the course. They may even signal to the community that the vaccine is intended for that corners are not being cut to launch the vaccine at the earliest.

In contrast, the vaccine which is being developed in Russia and codenamed Sputnik V also received a lot of publicity for being registered already, even though only the first two phases of the trial were conducted by then, which only had about 76 volunteers. Although early results were promising, a much larger trial is still necessary for finding out whether the vaccine is completely safe and effective.

Read more: Russia’s COVID-19 vaccine shows immune response; larger trials to follow

Although the initial sample size of the trials was small, the Russian vaccine candidate has produced positive results similar to other adenovirus vector-based vaccines being developed around the world. Larger trials are now underway to determine whether the vaccine is safe and effective.

Vaccines are usually distributed in one of two ways:

• Frozen
• Lyophilized (freeze-dried)

Both strategies have been previously used in large-scale distribution around the world. The decision on which of these will be used in this case will only be taken once the vaccines are ready and the right supply chain has been identified for its distribution in various countries and regions across the world. 

According to the NEJM panellists, the Russian government has been celebrating the development and early results of the Sputnik V vaccine though it is still under a larger phase 3 trial. That said, their decision to have the vaccine tested in various countries, including India, makes the trial more promising and robust.

More candidates for trials and testing around the world also gives hope in terms of the vaccines' effectiveness in multiple population groups.

A majority of the studies, guidelines and framework discussing COVID-19 have been around safety, precautions and development of treatment strategies. As vaccines candidates are still in development and trial stage, not much discussion has happened around how the vaccines could be distributed, or who gets them first.

The United States Centers for Disease Control and Prevention (CDC) recently issued a rough set of guidelines concerning the deployability of vaccines if and when they are available.

While the last quarter of 2020 has been tentatively put forward as the time when the first batch of vaccines may be deployed, it is also important to understand that only a small set of vaccines would be made available initially. And that batch of vaccines is usually prioritised for people who need it most.

Read more: WHO not expecting widespread distribution of COVID-19 vaccine before mid-2021

According to the CDC, around 1-3 million doses of vaccines may be made available at first, while another 20-45 million doses may follow towards the end of the year. Of course, these are desirable dates and do not guarantee anything. It is eventually the government as well as the state authorities who determine the rolling out of distribution strategies.

Who receives the vaccine first may be established by deciding which part of the population is most vulnerable to the severe complications of COVID-19. Going by Indian health ministry guidelines on COVID-19 so far, as well as the experience of previous disease outbreaks, this may include senior citizens, people with comorbidities like heart disease and lung disease, those who live in long-term care homes, and those who are disproportionately impacted by the disease such as the poorer sections of society and those at risk of severe COVID-19.

(That said, vaccines are typically less effective among older people. Scientists say this may have to do with how their T-cells—an important part of the immune system—respond to anything new. Some vaccines may also be contraindicated for some people. All of these factors can only be decided once the vaccine is ready and tested.)

Read more: What is Long COVID?

Vaccines must be deployed to those most at risk of complications, which means it also brings in healthcare and frontline workers, as it decreases the risk of them getting the infection. Thus, it is important for public health authorities to debate and arrive at a consensus over this.

Vaccines have been developed with similar levels of urgency as now during past outbreaks. The NEJM panellists mentioned that during the 2009 H1N1 outbreak that was spreading to many parts of the world (including India), a lot of planning went into who should get the vaccine first. However, the dates of delivery that were decided on were not met, and by the time the vaccine was available, the disease had already passed, and the highest priority group was not met. 

Guidelines over the distribution of vaccines were issued, but various states in the United States are governed by their own laws, and thus the guidelines were not implemented in the same way everywhere.

However, the distribution of vaccines and deployment can be different in the case of different disease outbreaks. The CDC made changes to its strategy against the influenza outbreak in 2017. In the case of Ebola virus disease which broke out again in recent years, there was a different strategy to contain the viral infection. The nature of transmission of Ebola is different from COVID-19, and it was controlled through effective contact tracing and a ring vaccination strategy—which made it possible to control the outbreak with only a limited amount of vaccines.

However, there has been distrust among various communities in West Africa. The Democratic Republic of Congo, where the disease had spread, is experiencing a new outbreak in recent months, but the strategies to contain Ebola are very different from efforts to stop the spread of COVID-19 even now.

Based on various vaccine strategies to control disease outbreaks previously, it is understood that certain individuals must receive vaccinations before others due to their exposure or risk of suffering greater complications from the disease. Based on the CDC’s early recommendations in the past as well as in discussions, the following strategy has been proposed:

1. High-risk individuals and healthcare workers 
2. Comorbid people and at-risk communities, and overcrowded settings
3. Young adults and children, and essential workers
4. Everyone else

However, for the effective distribution and deployment of vaccines when they are indeed made available, it is equally important that local communities and populations be trusting of the research that has been done in the development of the vaccines. Adequate infrastructure has to be created so that communities with high transmission rates are covered first, to break the chain of transmission.

The main focus of a vaccination programme is always to reduce the immediate risk of mortality as well as morbidity due to the transmission of a pathogen, which is SARS-CoV-2 in this case. Although the vaccine distribution plan discussed above is still under discussion, it is equally important that countries—India included—conduct more debate on local and national levels.

Read more: ChAdOx1 nCoV-19 vaccine gets DGCI nod for testing in India

In highly populated countries like India, where cases have been rising steadily over the last few months, it is important for communities to buy into the strategies being developed at the national level, to make them understand that the vaccines are going to be distributed, and everybody may not receive them at the same time.

People who are exposed to the virus or are at risk of developing severe complications from the disease or are highly vulnerable are always the first to be vaccinated so that they can be saved. 

And as vaccines are closer to being a reality in the months to come, it is important for the country’s leadership as well as the public health community to have these debates and discussions over the distribution and deployment of vaccines when they are eventually available to at least a section of the public.