By Dr. Charuni Kohombange    Along with the emergency use approval of the Covid-19 vaccines, the biggest vaccination campaign in history is currently underway. At the time of writing, more than 3.01 billion doses have been administered across 180 countries. The latest rate of global vaccination rollout is around 43.2 million per day. Although enough doses have now been administered to fully vaccinate 19.6% of the global population, the distribution has been lopsided.  According to the current data, countries and regions with the highest incomes are getting vaccinated more than 30 times faster than those with the lowest. However, an equitable vaccine rollout plan is essential across the globe to achieve global immunity at a considerable level. Sri Lanka has administered more than 3.5 million doses so far.   This article is focused on the rollout of the Covid-19 vaccine and to debunk any myths regarding vaccines. The article excerpts an interview with University of Colombo (UoC) Faculty of Medicine Department of Community Medicine Head Prof. Manuj C. Weerasinghe and Sri Lanka Medical Association (SLMA) Immediate Past President and Organisation of Professional Associations (OPA) Vice President Prof. Indika Karunathilake.     [caption id="attachment_147033" align="alignright" width="270"] SLMA Immediate Past President and OPA Vice President Prof. Indika Karunathilake[/caption] The role of a vaccine in preventing the spread of Covid-19   Most of the successful vaccines can prevent the spread of a particular disease at a high percentage, yet it is a percentage less than 100%.   The impact of the vaccine on the spread of the virus can be observed after six months from the initiation of the programme, assuming nearly 80% (based on the principle of herd immunity) of the total population is vaccinated. Also, the manufacturers of vaccines that are used islandwide (AstraZeneca Covishield, Sputnik V, Sinopharm) state that these vaccines will reduce the pathogenicity of the virus within the body, the severity of the symptoms, and the probability of fatalities but not the probability of getting infected. Therefore, whether you are vaccinated or not, it is still important to adhere to the new norms of living with Covid-19.     The action of the vaccine within the body of a person  A vaccine mimics the virus since it carries antigens specific to that particular virus. Hence, the body would produce antibodies specific to the attenuated viral antigen, which would protect the individual from a future infection of the same virus.   [caption id="attachment_147034" align="alignright" width="268"] SLMA Vice President and UoC Faculty of Medicine Department of Community Medicine Head Prof. Manuj.C.Weerasinghe[/caption] In the majority of the mass-produced vaccines, spike proteins of the virus are used as the antigen. Attenuated antigens administered through vaccines are first recognised by the sentinel cells of the immune system and they will uptake and present the relevant antigen segments to naïve immune cells (B and T Lymphocytes) which would sensitise those cell types and initiate an immune response against the particular antigen. This action would prevent the subsequent infection by the same virus that carries antigens similar to those administered through the vaccine through immunological memory. Since the immunological memory declines with time, the second dose is administered as a booster to trigger the secondary immune response of the immune system, which provides a highly specified defence against the relevant virus.     Factors need to be considered when prioritising the recipients  The priority list was prepared by the National Committee for the Prevention of Infectious Diseases of the country. This also acts as the chief committee consulted by the Government to provide it with relevant proposals in preventing infectious diseases. This technical committee was responsible for implementing the national vaccination policy against Covid -19 and the relevant priority list of recipients of the particular vaccine. The ability of a manufacturer to supply vaccines in numbers matching the requirements was primarily used as the major aspect when prioritising.   In the original road map, priority was given to;

•         Frontline workers from health and security sectors 
•         People suffering from chronic illnesses such as diabetes who are above 60 years 
•         People above 60 years of age 
•         People between 30-60 years with chronic non-communicable diseases 

  Vaccine rollout plan  There should not be any deviation from priority groups identified in the original vaccine rollout plan, and this plan is based on the availability of vaccines.   Up to 3% supply: Healthcare (government, private) and other non-health key frontline workers actively involved in Covid-19 outbreak management and other key essential services providers  3-10% supply: Healthcare (government, private) and other non-health key frontline workers actively involved in Covid-19 outbreak management and other key essential services providers, comorbid elderly population above 60 years, to prevent mortality and severe complications   11-20% supply: Healthcare and other non-health key frontline workers actively involved in Covid-19 outbreak management and other key essential services providers, comorbid elderly population above 60 years not covered by initial supply  20% supply: Add other comorbid risk categories, below 60 years (diabetes, neoplasms, CVD, chronic renal diseases, structural lung diseases). The age cohort of 50-59 years will be prioritised first  >20% supply up to 50%: Add essential service providers not covered by initial 20%, (workers in) special working environments with outbreak potential (factories and other congregate settings), population categories with the outbreak potential environment (university students, people in areas with high population densities)  Since vaccines are in short supply and will be for some time, prioritisation of target groups with clarity will be the most important thing. A clear vaccine rollout action plan based on the defined prioritisation criteria, accompanied by a sound communication strategy would be essential.     FAQs regarding vaccination    Vaccinating patients with chronic illnesses  Vaccines must be given to patients with chronic illnesses, including cancer patients, to reduce fatalities and to avoid severe symptoms. Recipients are advised to reveal their true medical conditions to the health workers who are administering vaccines to them.   Vaccinating patients with a history of allergy  As far as allergies are concerned, only the people with a history of severe allergies are considered risky to vaccinate and the vaccine would be administered in a safe space with emergency treatment facilities. For others with minor allergies, such special conditions are not mandatory.   Vaccinating pregnant mothers  Pregnant mothers in their second or third trimesters should also be vaccinated. There is no evidence for the occurrence of infertility in the recipients.   Children   The National Medicines Regulatory Authority (NMRA) is yet to decide on the vaccination of children.    Possible side effects  When vaccinating millions of people, we could expect a few effects to develop. Rare side effects develop in less than one per 10,000 people vaccinated. Based on worldwide evidence, the benefits still outweigh the risks.     Vaccination of patients who have recovered from Covid  It is effective to administer the vaccine to a recovered person after four to six months since recovery, since the vaccine may get inhibited by the antibodies present in the body if vaccinated immediately after recovery.     Regarding those who were unable to receive the second dose of a given vaccine  When considering the AstraZeneca vaccine, currently, there’s a situation where we lack around 600,000 vaccines that need to be administered as the second dose. It is because the largest manufacturer of the vaccine, the Serum Institution of India, is unable to meet the current requirement amidst the Covid crisis in India.  Earlier, it was decided that the second dose of Covishield must be administered within four weeks after the administering of the first. However, with further research, it was found that the effects of the first dose can retain immunological memory within the body for at least 16 weeks. Under these circumstances, and the assurance given by the Serum Institute to keep a continuous supply chain, the health sector had decided to administer another 300,000 doses from what they’ve stored as the second dose. But unexpectedly, since the Serum Institute failed to maintain the supply chain, it created this crisis where nearly 600,000 people were missing their second dose.  However, with the current evidence, there is a possibility of administering the second dose using the Pfizer or Moderna vaccines, which is acceptable and may even produce a better immune response.    Unlike the other two vaccine types, Sputnik V is a two-component vaccine which uses a different component as the second dose. In Russia, due to problems in manufacturing the second dose of the vaccine, the availability of the second dose is in a doubtful situation.     Developing immunity after the first dose  When considering the protection given by each vaccine after administering the first dose, the Sinopharm vaccine does not offer any primary protection, but immunity would increase after two weeks of administering the second dose.   For the Sputnik V vaccine, it’s been found that considerable immune protection is provided even after the first dose.  Targeted and systematic immunisation of vulnerable populations against Covid-19 will be the most important intervention to reduce deaths.     Challenges and the good practices   The delay in testing, late PCR reports, and late hospitalisation may lead to long exposure periods. Hence, in the present strategy, in which the areas selected are based on current disease transmission, most of the people who come for vaccination may have already been exposed.  It is unlikely that we will have adequate supplies of vaccines to provide the required number of doses to a reasonable proportion of the population until December 2021.  The most vulnerable – the uneducated elderly who have other priorities – may not join the long queues in the current strategy and the elderly people with comorbidities may not join the long queues, while the young people in their households, who are mobile, may take the infection home, even if they are vaccinated.  The elderly people with comorbidities will be late to come for treatment and they will die at home or will end up in the ICUs if admitted to a hospital.  It is likely that we may experience more waves in this pandemic due to various reasons – clustering of asymptomatic patients, introduction of new variants, etc. Hence, those who miss immunisation in this round may get the infection in the next wave.  Unless the immunity level of vulnerable populations such as the elderly and the people having comorbid conditions is improved, they will continue to get exposed to the infection and will end up in ICUs.  In the absence of a realistic vaccine supply chain with a timeline, all the vaccines received should be deployed with extra caution, keeping the second dose in storage. From every consignment of vaccines received, the second dose of vaccines should be reserved before the rest is distributed for deployment (when applicable).   Vaccination is a public health strategy and the decision-making and implementation should be with the public health system of the country and with other stakeholders providing assistance.    (The writer is the Medical Officer for Healthcare Quality and Safety at the Ministry of Health)