Blog 28 May, 2021 Back
Global vaccination is crucial to ending the COVID-19 pandemic.
The single best strategy to stop the spread of COVID-19 and its new variants is to drive infection rates as low as possible, thereby limiting the opportunities for mutations. When a large proportion of the community becomes immune to a disease, the spread from person to person becomes unlikely. This is known as herd immunity, and the two main paths to herd immunity are infection and vaccines.
Herd immunity is reached naturally when enough people in the population have recovered from a disease, developing protective antibodies against future infection. It can also be reached when enough people have been vaccinated against a disease and have developed protective antibodies against future infection.
Unlike the natural infection method, vaccines create immunity without causing illness or resulting complications. Using the concept of herd immunity, vaccines have successfully controlled contagious diseases such as smallpox, polio, diphtheria, rubella and many others.
Remarkably only 18 months after the start of the global COVID-19 pandemic, there are now multiple vaccines available, this is the fastest vaccine ever created – more than 170 different coronavirus vaccinations are currently in trials.
How does the Coronavirus vaccine work?
All the vaccines have the same approach – fooling our bodies into thinking we’ve been infected with coronavirus.
This enables our immune systems to build a memory of COVID-19 so it is able to fight against it in the future.
There are 4 main types of COVID-19 vaccine
1. Whole Virus
2. Protein Subunit
3. Viral Vector
4. Nucleic Acid (mRNA)
Some of them work by smuggling the antigen into the body and others use the body’s own cells to make the viral antigen.
Whole Virus – this vaccine inserts a dead or inactive version of the SARS-CoV-2 virus into the body, triggering an immune response. This vaccine is difficult to produce, as Dr David Matthews, virologist from the University of Bristol, explains: “To make a huge amount of a highly dangerous virus and then kill it – making sure it’s definitely dead – is a massive task.”
Protein Adjuvant (Subunit) vaccines rely on teaching your immune system to recognise SARS-CoV-2’s protein spikes by inserting protein spikes into the body. The process of creating the vaccine involves growing cells that are expressing spikes then purifying the spike away from the other parts of the virus.
Viral Vector – this type of vaccine has been created by Oxford University-AstraZeneca and injects your body with a genetically altered common cold virus from chimpanzees (called an adenovirus). The lab-modified virus carries genetic instructions to create the protein spikes found on the coronavirus. After injection, the vaccine virus enters a human cell. There it uses the cell’s nucleus to ‘photocopy’ the genetic instructions of how to make the coronavirus protein spikes, causing the cell to produce its own spikes, prompting the body’s white blood cells to attack it. Therefore, if confronted by a real COVID-19 outbreak, your immune system can recognise these spikes and has a tried and tested battle plan.
Nucleic Acid or mRNA vaccines are the type developed by Pfizer and work in a similar way to a viral vector vaccine, prompting your body’s cells to produce coronavirus spikes. Unlike the viral vector, the mRNA injects a collection of instructions that enters a few of your cells provoking an immune response, instead of forcing cells to ‘photocopy’ genetic instructions.
To date, seven major vaccines have shown promising results in protecting people against COVID-19.
1. Pfizer-BioNTech (mRNA). After conducting their final efficacy analysis, the two drug companies announced their vaccine is more than 94 per cent effective in over 65’s. The findings were based on a study of 41,000 participants around the globe.
2. Oxford University-AstraZeneca (viral vector). The vaccine was shown to be, on average, 70 per cent effective in an analysis of phase 3 trial data. While administering two full doses of the vaccine a couple of months apart yielded 62 per cent effectiveness, a half dose followed by a full one later showed to be 90 per cent effective.
3. Moderna (mRNA). In a trial of more than 30,000 Americans, the vaccine showed to be nearly 95 per cent effective.
4. Valneva (inactive whole virus). The vaccine has been trialled on 150 volunteers at testing sites in Birmingham, Bristol, Newcastle and Southampton, with early results showing 90 per cent immune response. Valneva will expand the study to 5,000 people in phase 3 testing.
5. Novavax (‘subunit’ or protein adjuvant). The vaccine has been shown to be 89.3 per cent effective in large-scale UK trials. Significantly, it is the first jab shown to be effective against the new UK variant of COVID-19 in such a trial.
6. Janssen (viral vector). The one-shot vaccine, developed by American manufacture Johnson & Johnson, has been shown to be 66 per cent effective at preventing moderate to severe COVID-19.
7. Gamaleya/Sputnik V (viral vector). In a press release, the Gamaleya National Center of Epidemiology and Microbiology in Moscow claimed a large-scale Russian study saw 92 per cent efficacy for its vaccine. However, other scientists have voiced concerns this claim is based on too few cases. Although the vaccine was trialled on 18,000 people, the efficacy claim has been based on an analysis of only 39 individuals to test positive with coronavirus.
Many other companies are also developing vaccines, with major trial results yet to be announced.
As long as COVID-19 continues to circulate, the risk of new variants will not go away. Each infection gives the virus another opportunity to mutate, and the larger-scale fears are of variants that evade immune responses or are more transmissible or deadlier to a greater number of people.
These variants could affect not only the effectiveness of the vaccines, but also the natural immunity that COVID-19 survivors have developed, making annual booster shots required for COVID-19 immunity.
If we reduce the amount of virus everywhere, we reduce the opportunity for it to mutate and potentially produce new variants of concern. To ensure that COVID-19 is unable to spread, we need to ensure vaccines are rolled out on a global scale. Countries can share excess doses through COVAX The COVID-19 pandemic is global and to bring the pandemic to a close, a collaborative, global approach is needed.
As individuals, we all need to continue to do everything possible to prevent infections and minimise the spread of coronavirus. By taking protective measures, such as washing hands, wearing masks and adhering to social distancing, as well as being vaccinated as soon as you are invited to do so, we should drive infection rates as low as possible, thereby limiting the opportunities for mutations.
Super Carriers and Spreaders
Recent research carried out by PNAS (Proceedings of the National Academy of Sciences of the USA) have found just 2% of SARS-CoV-2−positive individuals carry 90% of the virus circulating in communities.
Based on the analysis of data from saliva-based COVID-19 screening deployed on the University of Colorado Boulder campus, this dataset is unique in that all SARS-CoV-2 positive individuals reported no symptoms at the time of saliva collection and therefore were infected but asymptomatic or pre-symptomatic.
The findings found that:
1. The distribution of viral loads observed in the asymptomatic college population was indistinguishable from what had been reported in hospitalized populations.
2. Regardless of symptomatic status, approximately 50% of individuals who test positive for SARS-CoV-2 seem to be in non-infectious phases of the infection.
3. Just 2% of infected individuals carry 90% of the virions circulating within communities, serving as viral “supercarriers” and likely also super-spreaders.
We have more information on our COVID-19 resources pages as well as guidance from numerous sources, this page also has advice from our own team of medical professionals, risk analysts and updates on the latest travel advice.