Covid-19: Single vaccine dose is 33% effective against variant from India, data show
BMJ 2021; 373 doi: https://doi.org/10.1136/bmj.n1346 (Published 25 May 2021) Cite this as: BMJ 2021;373:n1346Read our latest coverage of the coronavirus pandemic
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Dear Editor
Mambisa vaccine candidate, developed at the Center for Genetic Engineering and Biotechnology (CIGB) in Cuba, is one of the five nasal administration that have reached the stage of clinical studies in the world.
The formulation is also the only one of its kind based on the platform of recombinantly produced antigens. Said technology has the main advantages of safety (with slight adverse effects recorded) and the possibility of giving multiple doses in order to reinforce the immune response over time.
Another benefit is its potential to induce this type of action in the nasopharyngeal mucosa, something particularly convenient, since it is a vaccine candidate against a disease whose entry point is through the respiratory tract. In 2015, the CIGB registered HeberNasvac, the first nasal administration therapeutic vaccine obtained in the world against a chronic infectious disease (chronic hepatitis B).
For the development of Mambisa, one of the proteins that are part of the referred product was used: the nucleocepsid or protein that makes up the nucleus of the virus, which has the ability to stimulate the immune response. Currently, this vaccine candidate has completed the phase 2 clinical study carried out at the National Toxicology Center (Cenatox). At this stage, the drug demonstrated a good level of safety and preliminary results revealed an effective immunological action.
Likewise, in studies carried out with people who suffered from the disease during the first peak of the epidemic in Cuba, Mambisa proved to be a good candidate for strengthening the immune system with the administration of a single dose.
Taking into account the simplicity of its use and high safety, this immunogen could serve as a reinforcement of immunization schedules with other vaccines that, due to their nature or the adverse reactions they cause, cannot be used in multiple applications.
Coordination with the Hermanos Ameijeiras Hospital and the health area of the municipality of Centro Habana, in this capital, are already underway for a phase II / III clinical study in people previously infected with the virus.
Those selected people will receive a single dose of the vaccine candidate Mambisa, with the purpose of evaluating the safety and capacity of that single administration to enhance immunity.
Kind Regards
Competing interests: No competing interests
Dear Editor
In the midst of the race for effective vaccines to help stop the spread of SARS-CoV-2, the emergence of mutant strains of the coronavirus has posed an even greater challenge to the international scientific community, as they question whether candidates under development will be effective against these genetic variants.
By itself, this phenomenon is sufficient to continue to drive the development of new immunogens. But, what strategies does Cuban science develop in the face of the appearance of the new strains of the coronavirus?
This is a real problem and there are many strategies to try to combat the virus mutation problem. The simplest is to have high levels of immunity.
Precisely Cuban vaccines have this advantage because they are recombinant, because if necessary, booster doses of vaccine can be given to maintain high levels of antibodies.
There are other technologies that are limited in that regard. In simpler terms, our vaccines so far have been shown to induce high levels of antibodies in vaccinated because booster doses can be given, and in time, when the immune response relapses, other doses can be administered.
Our candidates have these benefits, but work is being done on vaccine candidates based on mutated viruses.
That is, it can be substituted or added to the current vaccine candidates, and to the protein with the mutation. To this, it is added that work is being done on the development of vaccines based on cellular responses. “It is another type of vaccine candidate that is more protective Cross, reactive Cross; I mean that, it can protect against different strains since the cellular response is more conserved than the antibody response between different strains.
In this sense, the CIGB is promoting a project with China, in one of the joint research centers, for the development of a PanCorona vaccine candidate, which aims to protect against the different strains of SARS-CoV-2, not only against the coronavirus that is circulating today.
Predictions indicate that we will unfortunately have to face other epidemics of new coronavirus strains in the future. This would be a vaccine that includes conserved regions in different coronavirus strains, both for antibodies and for cellular response, and therefore it is thought that it can protect against different strains and other new ones that appear.
That is the goal. All these strategies are the ones that give strength to be able to be prepared for possible mutants or new emergencies.
Kind Regards
Competing interests: No competing interests
Dear Editor,
Without some behavioural modification it might be impossible to achieve population immunity against covid, despite the vaccine rollout. If new variants of concern are either more transmissible or more vaccine resistant than their predecessors then we will need greater vaccine uptake to have the same effect. The spread in the UK of SARS-CoV-2 variant of concern B.1.617.2, the “Indian" variant, makes it even more important to vaccinate as near to 100% of the UK population as possible.
Coronavirus ceases to spread when the R number falls below 1. At the start of the pandemic, R0 was estimated to be around 2.4 in the UK. The Indian variant is suspected to be more transmissible than the original new coronavirus strain. This means that it will be even harder to achieve population immunity and the intrinsic transmissibility of the virus needs to be even more strongly combated by preventive behavioural measures and vaccination. With vaccination, the virus will stop spreading provided that R0 x (1-VExVP)<1, where VE is the vaccine efficiency and VP is the proportion of the population who have been fully vaccinated. If this condition is satisfied without the need for behavioural restrictions then population immunity has been achieved.
It seems that the Indian variant of the virus is likely to become the dominant one in the UK. For this variant, recent figures [1] from the PHE estimate Vaccine Efficiency, VE, after second dose of vaccine to be around 60% for the AZ vaccine and around 88% for the Pfizer vaccine. Taking the average of 74% as a very rough estimation of VE would indicate that to achieve population immunity would require vaccine uptake of roughly 81% for R0 = 2.5; or roughly 98% for R0 =3.6 (in the case where 50% higher transmissibility of the Indian variant puts R0 50% higher). Clearly, if it is necessary to give two doses of vaccine to between 81% and 98% of the population in order to achieve population immunity then this will be difficult to do, and we haven’t got there yet.
Until this high vaccine uptake is achieved we are relying on behavioural restrictions to reduce R. Any further relaxation of restrictions is likely to result in an increase in covid cases unless two doses of vaccine have first been given to a high proportion of the population (very roughly estimated at 81%-98%). As more data is collected the statistics will become more accurate, but the general conclusion will likely remain. Until the vast majority of a population, whether nationally or locally, has had two doses of vaccine there is a risk of an increase in case numbers of SARS-CoV-2, particularly in B.1.167.2, the Indian variant.
Reference
[1] https://www.gov.uk/government/news/vaccines-highly-effective-against-b-1...
Competing interests: No competing interests
Re: Covid-19: Single vaccine dose is 33% effective against variant from India, data show
Dear Editor,
I read with a mix of interest and sadness the article on the spread of the new vaccine-resistant variant in India.
Reading the whole slew of articles about the arms-race that has ensued in our fight against the variants (see [1], [2], [3] for others) has made me wonder to what extent our (1) behavioural modifications and (2) mass vaccination programme have contributed to the emergence of transmissible and vaccine-resistant variants.
Given the fact that our novel-technology vaccines are aimed at a very specific antigen of the virus, as opposed to inducing a wide immune response (e.g. through responses to live attenuated virus or natural infection), one would imagine it is not evolutionarily expensive for the virus to change its signature to become undetectable and thus resistant. Thus, it is hard to see how we would be able to emerge victorious from this arms-race. Is this time for us to pause and rethink our strategy?
I look forward to hearing the opinions of other enlightened scientists in this matter.
[1] Delta variant now dominant strain in UK, BMJ, https://www.bmj.com/content/373/bmj.n1445?int_source=trendmd&int_medium=...
[2] Vaccines to be tested against variants, BMJ, https://www.bmj.com/content/373/bmj.n1163?int_source=trendmd&int_medium=...
[3] Variant-vaccine race in the US, GenomeWeb, https://www.genomeweb.com/scan/variant-vaccine-race-us?utm_source=TrendM...
Competing interests: No competing interests