Unprecedented discovery and rollout of effective vaccines against COVID-19 have provided us a glimpse of hope that the end of this pandemic is probably in sight. Historically, the smallpox pandemic took 200 years before it was finally eradicated from the face of the earth after mass vaccinations. We can only hope that the COVID-19 pandemic will end in our lifetime.

The global flu pandemic of 1918-1919 infected 500 million people and killed 50 million before that pandemic ceased and after it infected enough people, and probably the viruses evolved and mutated into less lethal strains. The very first flu vaccine was not invented until 20 years after the flu pandemic ended, and it was only in 1973 when WHO began issuing guidance to all nations on the composition of the flu vaccine for each coming flu season. Fast forward to today, we are still receiving flu vaccines annually to afford protection from acquiring severe flu infections.

A year from the anniversary of the COVID-19 pandemic, there were already 127 million people infected and 2.8 million deaths globally. We are still witnessing regional lockdowns due to the second and third waves of the pandemic in various parts of the world. The director of the Centers for Disease Control and Prevention warned of “impending doom” from a potential fourth surge of the pandemic in the U.S. if the current trends persist.

Scientists have predicted that when enough people get immunity either by natural infection or vaccination, the infection will slowly die out because it is harder for the virus to find new susceptible hosts. This is what we call herd immunity. In other words, the virus will eventually run out of people to infect. The current understanding is that only an effective vaccine will put an end to this pandemic, but how we get there remains to be seen.

Currently, only 463 million doses of vaccines were delivered out of 7.9 billion people in the world. This is only 5.8% of the entire world population. Many hindrances may delay reaching the potential goal of herd immunity, according to experts.

For one, vaccine adoption may prove lower than expected in some parts of the world. Some people have perceived safety issues and hesitancy in receiving the vaccine. Second, herd immunity relies on the efficacy of the vaccines in reducing transmission and not only by preventing disease. The currently available vaccines have variable efficacy rates and may not prove high enough to drive herd immunity. Third, the duration of vaccine-mediated immunity may prove shorter than anticipated, making it hard to reach the necessary threshold for simultaneous immunity. Fourth, supply-chain disruptions and delays in delivering vaccines in many parts of the world, especially Third World countries. Fifth, most concerning, variants that may reduce the efficacy of vaccines. Current known variants of SARS-COV- 2, including the UK, South African, South American and Californian, appear to be more infectious than the original wild-type strain.

We still do not know the impact of vaccines against severe diseases from these strains. If the existing vaccines are found to be less effective on these strains, it will pose a substantial risk to lives and could delay the end of the pandemic.

Many scientists believe that the SARS-CoV-2 is here to stay, and it may appear seasonally, just like the flu virus. There are still many unknowns when it comes to this virus, and we are still unsure if the coronavirus will behave similarly to the flu viruses. If this is the case, we may need to get COVID-19 shots annually to obtain adequate protection since we still do not know how long the currently available vaccines will provide defense or shield us from getting very sick.

We still have a long way to go before we can put the pandemic to rest. Until we vaccinate all people, this will continue to circulate as people start to mingle and travel. Isolated clusters or regional cases may still occur, and the virus may continue to circulate for one or more quarters after herd immunity is reached. Viral epidemics will remain a regular feature of our human life. As a collective society, we can only hope that we have learned great lessons sufficiently well to quell future challenges.

Dr. Ramel Carlos is a board-certified neurologist practicing in Guam for 18 years and a specialist in epilepsy and clinical neurophysiology. He is also a pediatrician, a diplomate of the American Board of Disability Analysts and the editor-in-chief of The Guam Medical Association Journal.

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