How effective are the Covid vaccines for our global immunisation efforts?Mar 23, 2021
While there are more than 200 vaccines against Covid-19 being developed, there are now seven vaccines being widely distributed and used around the world. Do they all work? That depends on how you judge “works” often described in terms of “efficacy” in achieving desired goals.
Let’s look at the characteristics of a perfect Covid 19 vaccine.
Two weeks after one injection antibodies that can neutralise the virus would be present in tissues such as those of the lung and also be in our saliva, nasal secretions and airways so that we could not carry virus in these secretions and possibly infect others even if we ourselves are protected. Being reasonable we would not be critical if this outcome needed a second injection a few weeks after the first to further expand the repertoire of immune cell required.
Perfect protection would result in us not having any mild or severe “cold” like symptoms if we were to be infected and would guarantee that meeting the virus would not see us become so sick we would need hospitalisation and certainly would guarantee that we would not die from an infection. The protection for the person vaccinated should last at least six months no matter what variant of the virus we encounter and protection would involve the persistence of antibodies and T cells that can kill virus infected cells.
No vaccine with all these properties has as yet been developed. However, remarkably, given the short time it has taken to develop these candidates, they all protect us from getting seriously ill should we be infected with no need for hospital care. Vaccinated individuals will not die if infected. I say, “all” though there remains some controversy about the two Chinese vaccines which we will explore.
While there is much that is disturbing about the government/bureaucratic goings on in China and Russia it is important to understand how the globalisation of good science has allowed for rapid vaccine development that’s unprecedented. Many of the top scientist developing Covid vaccines have worked for years internationally. There are outdating scientists in Russia and China. The woman who runs the virology lab in Wuhan worked in Montpellier for 12 years and is universally respected.
Russia appears to be having massive distribution problems for its “Sputnik V” vaccine but the latest data on this vaccine published recently in the Lancet found that it had a higher efficacy rate than the Oxford-AstraZeneca vaccine that many Australians will receive, which is between 63 and 70 per cent.
All of us have personal interest in the success or otherwise of global immunisation as success will be necessary for us to return to the freedoms associated with a pre-Covid world.
Most of the people on our planet are being immunised with either the Russian or Chinese vaccines though the COVAX program being run by the WHO is having some success in getting more Western vaccines distributed to poor countries.
Our government has announced that Australia will send 8000 doses of the locally produced AstraZeneca vaccines to PNG to help immunise health workers, as well as personal protective equipment and teams of health workers to help fight the widespread PNG outbreak. Perhaps one in three citizens in that country are already infected.
Our contribution is at ‘token’ level but we also asked the EU to redirect I million doses of the European produced AstraZenica vaccine, originally contracted by the Morrison government for use in Australia, to PNG. We are yet to hear if the EU will oblige but at the moment it is unlikely as the EU is trying to hold all European produced AZ vaccine for the severe outbreaks that have reoccurred in Europe. We are going to rely on locally produced AZ vaccine four our mass immunisation program; how fortunate we are to have the capacity to do so. Our CSL hopes to produce 50 million doses of the vaccine by the end of the year.
So what about the Chinese vaccines?
While at least 13 companies in China are developing vaccines only two are being widely used; CoronaVac produced by a company called Sinovac Biotech and another provided by Sino Pharm. For the latter published data from phase 3 trials in China itself, the UAE, Bahrain and Peru suggest that the vaccine has an efficiency rate of 79%.
The data on the CoronaVac vaccine is more variable perhaps because so many of the efficacy studies have been done in developing countries. Figures for efficacy range from 51% to 91%. Indonesia reports 65% and Brazil 78% efficiency. Both vaccines are made from inactivated SARS-COV-2, the ‘old fashioned’ way but are easy to store and are being made available for a reduced cost to more than 60 developing countries as part of the Silk Road Covid diplomacy initiative of China which is certainly winning friends . At this time we would say that these vaccines are indeed stopping people from getting ill and dying from Covid-19.
Growing evidence suggests that having a first injection with one vaccine and a second with another vaccine may see a significant boost to the immune response with fewer side effects.
So let’s look at where we are with our efforts to protect Australians from Covid-19. We are currently immunising cohorts at most risk of contracting a Covid infection with the Pfizer vaccine. ( Quarantine workers, nursing home residents, from line health personnel etc) This decision was based on studies that showed that the Pfizer vaccine may be more efficient than the AstraZenica vaccine in protecting one from severe Covid infections.
This conclusion is now disputable as new data from the UK shows little difference between the two vaccines in preventing infections that would require hospital care. The important conclusion is that while we may get a ‘cold’ like illness even after immunisation we will not see hospitals swamped with seriously ill patients and not have people dying from the disease . This will give us confidence to be far less restrictive when a local outbreak occurs with no need to close borders and institute the dreaded ‘lockdowns’ of the last twelve months.
As of now we are vaccinating the cohort nominated as 1b with the AstraZenica vaccine.
Elderly adults aged 80 years and over
Elderly adults aged 70-79 years
Other health care workers
Aboriginal and Torres Strait Islander adults over 55
Adults with a specified medical condition
*People will need to provide proof of these conditions to demonstrate their eligibility for vaccination via My health record, a health professional referral if required or a declaration form.
Adults with a disability who have a specified underlying medical condition
Critical and high risk workers including defence, police, fire, emergency services and meat processing
The AZ vaccine is safe and provides close to 100% protection from serious illness if exposed to the SARS-COV-2 virus. This includes exposure to all the so far discovered variants of the virus. You will need two doses of the vaccine and it is likely that you will have some local soreness at the injecting site and maybe a mild fever. Neither is a serious issue.
While manufacturers of both the Pfizer and AZ vaccine suggest that early studies show a reduction in the immunised of the carriage of infectious virus in ones nasal and respiratory secretions, the data is soft and in any case around the 60% mark. This is a crucial issue. It means that while we might be protected from Covid the unvaccinated we encounter could be at risk of infection from highly contagious virus we might still secrete into the air.
You may have seen the extraordinary exchange last week between the American infectious distress expert Dr Tony Fauci and the troublemaker Senator (Dr) Rand Paul in a senate hearing wherein Paul criticised Fauci for advising that with just 12% of thy population fully immunised it was crucial that those who were protected continue to wear masks in public and practices social distancing. Paul shouted at Fauci that wearing masks after immunisation was merely theatrical completely misunderstanding the potential for the vaccinated to continue to spread the disease. We have discussed vaccine hesitancy before in P & I but we need to do all we can to have 80% of Australians vaccinated to really contain the epidemic.
Safety studies on vaccinating children aged 12 to 18 have been completed and no safety issues were discovered. The manufacturers of the Moderna vaccine are nearing completion of trials of this vaccine in babies 3 months or older and children under 12 and so far all looks good for childhood vaccination.