‘Vaccinate as many as possible as threshold for COVID-19 herd immunity not known’

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The United Kingdom (UK) became the first country in the world to authorise the use of a COVID-19 vaccine when it gave a green light to the Pfizer-BioNTech vaccine for use on the general public. The UK currently stands 7th in the world, as far as the number of coronavirus cases is concerned (1,705,971), and 5th when it comes to the fatalities (61,014).

Jennifer Okoye, a PhD student at the University of Nottingham, in a conversation with TIMES NOW, said that the numbers surrounding the spread of COVID-19 in the UK must have added pressure on the govt to push to be the first to authorise the vaccine.

“In terms of COVID-19 deaths per 1,00,000, the UK is the seventh-highest country globally, behind Belgium, San Marino, Peru, Andorra, Spain and Italy. But in terms of the total number of deaths, only the US, Brazil, India and Mexico have recorded more deaths than the UK, according to Johns Hopkins University. With only the US and Belgium having a higher gross domestic product (at purchasing power parity) per capita, these numbers would indeed add pressure to the UK government to push to be first in line for the vaccine,” she said.  

Okoye, who is doing her PhD in virulence factors of zoonotic campylobacter and their interactions, further said that while the UK has decided to go with the Pfizer-BioNTech as well as the Oxford-AztraZeneca vaccine, other vaccines that are in the final trial phases, are most likely to be put to use as well.

“The UK has decided to go with both the Oxford-AZ vaccine (100 million doses) and the Pfizer vaccine (40 million doses). Certainly, the other vaccines that are currently in phase 3 will be ordered as they pass the MHRA stage too. It has been said that multiple lines of defence will be needed to tackle the virus, and that means using more than one type of vaccine,” Okoye said.

The oxford-AZ vaccine, she said, “will be released later because they had to pause for investigation of some side effects in their phase 3 trial, they are back on track now but behind Pfizer in the ‘race’.

Who should be vaccinated first – Healthcare workers or elderly people?

When asked about the question that most governments around the world are likely to face, as they plan the distribution of the vaccine, about who to vaccinate first, Okoye said, “both elderly and healthcare workers should be vaccinated side by side.”

“Although elderly people in care homes and care home staff have been named as a priority, followed by over-80s and healthcare staff, it is probably healthcare staff and those already in the hospital that will get the vaccine first as they already have the necessary storage facilities – the freezers that can reach as low as -70 deg C,” she said.

Logistics surrounding the cold storage facilities.

“Getting the Pfizer vaccine to individual care homes (in the UK) would be a challenge because it needs to be stored at extremely low temperatures so with regards to care homes, the Oxford-Az and the Moderna vaccines may be more suitable as they do not need to be stored at such low temperatures. Here is an example of how the difference in cost and logistics will contribute in shaping which vaccine reaches different users,” she said.

If one has recovered after contracting the Coronavirus, will they still be needing the vaccine?

One of the most important question in people’s mind is will they still be needing the vaccine if they have already contracted the virus and have recovered? Will they be ‘naturally immune’ to the Coronavirus after recovery?

To this regard, Okoye said, “It is not yet known how long natural immunity lasts for after infection with Covid-19 so the Centre for Disease Control has recommended that even those that have been previously infected get the vaccine and booster jabs. There is also currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection. It is also not known how long immunity lasts after vaccination, that data is still being collated as we speak; researchers will need to monitor this closely in the coming months and years.”

The Pfizer-BioNTech vaccine reportedly shows 95% efficacy rate. What does this mean? Will this lead to a 95% ‘effectiveness’ when the vaccine is rolled out for the general public?  

In the last few days and weeks, we have heard a lot of numerical values about the ‘efficacy rates’ of various COVID-19 vaccines that are leading the race to be the first in the market. But how does this efficacy rate figure impact the general public when the vaccine is finally rolled out?               

When asked about this, Okoye said, “tests on more than 43,000 people have shown that the Pfizer vaccine is 95% effective at preventing disease when measured a week after its second dose. In total, the major vaccine trials have drawn effectiveness conclusions from only 200 patients although the trails have involved tens of thousands of people. These randomised clinical trial results are measured in ideal controlled environments, but vaccine efficacy does not always predict vaccine effectiveness i.e., the protection given by a vaccine administered non-randomly under field conditions. Breaking up that data into different groups — such as those with underlying conditions or the elderly would mean loss of statistical power, so it is hard to extrapolate to the real world unless larger surveillance is carried out once the vaccine is rolled out. Nonetheless, all three major vaccine leaders have surpassed the goal of 50% efficacy as well as proving to be safe – the gold standard for vaccines.”         

Finally – Do we need to vaccinate everyone?

Vaccination campaigns are nothing new, in the past, we have seen mass vaccination campaigns to eradicate some of the other diseases. But the question that needs to be asked is, will everyone have to get vaccinated in order to bring an end to this pandemic? Or will we, at some point of time, develop the herd immunity, therefore not requiring a vaccine after all.

“For most vaccine treatable viruses not everybody needs to be vaccinated to protect the population. This is called herd immunity,” Okoye said.

She further added, “Herd Immunity is a concept within vaccination programs whereby if a certain threshold of vaccination within the population is reached, then the whole community will likely be protected from that disease, even if not all members have been vaccinated. Vaccinating a high percentage of the population is important for protecting those that are most vulnerable, i.e. children under 1 year old, who can’t get vaccinated and are more susceptible to infection; the elderly, who have a higher risk of death if they contract vaccine-treatable illnesses; and people with weakened immune systems, who can’t get vaccines and are more likely to die from the diseases they protect against. Herd immunity is acquired by protecting people from catching the live virus, not by exposing them to it (this would be scientifically problematic and unethical).”

The percentage of people who need to have antibodies to achieve herd immunity against a disease varies.

“For example, herd immunity against measles needs around 95% of the population to be vaccinated, whilst for polio, the threshold is about 80%. The Centres for Disease Control and Prevention set the lowest threshold of vaccine coverage at 75% (for mumps). It is not yet known what the threshold for COVID-19 is so the strategy will be to vaccinate as many as possible,” Okoye said.

How long is it likely to take for the UK to vaccinate its 66.8 million people?

“Phase one of the rollout is targeted towards the 22 million people that make up the 10 priority groups, as determined by the UK Joint Committee on Vaccination and Immunisation (JCVI). With each person needing 2 jabs and the NHS planning on immunising 1 million people a week, if those in phase one were to begin immunisation now, the rest of the population in phase two (a further 45 million people) will most likely begin to receive the vaccinations from the middle of 2021. This is the best-case scenario,” Okoye signed off with.

While the UK may be the first country to put in motion, the COVID-19 vaccination program, sooner rather than later, every country will have to face similar challenges, answer similar questions and manage similar logistics. But 2020, the year which was consumed by one of the toughest challenges faced by mankind, in face of the COVID-19 pandemic, looks like ending on a note of hope.      

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