IO – For many people, the year 2020 is the worst year in their living memory. The covid-19 pandemic, coupled with economic meltdowns, has caused misery piled upon misery. Over 43 million people have been already infected, slightly more than a million people have died, and trillions of dollars in economic costs have been incurred.
Unfortunately, it’s set to get even worse, especially in countries situated in the Northern Hemisphere.
Just over the past few weeks, as winter has deepened across Europe and the United States, record- setting infections are testing the limits of health care systems and the ability of governments to contain the situation. The EU has recently managed to reach an agreement on a stimulus package to stave off an economic meltdown, and Congressional leaders in Washington are working feverishly to reach a deal on a new economic aid package. Meanwhile, in cities across the US and Europe, lockdowns with night curfews are being imposed or about to be imposed, and with the Christmas and New Year holidays right around the corner, nobody has any reason to cheer.
Yet, there is renewed hope, and reasonable cause for optimism, since the world discovered recently the results of the Pfizer and Modena vaccine trials, with both vaccines showing efficacy of approximately 95 percent. And, with new progress being made on therapeutic drugs as well, talk about the pandemic coming to an end next year is no longer a fantasy.
In the US, public health experts are saying that the positive news on the efficacy of these vaccines means America could possibly reach an epidemiological end to the pandemic, or herd immunity, in the third or fourth quarter of next year. Equally good news is that assuming president- elect Biden manages to convince state governors to implement stricter health protocols and manufacturers of new treatments are able to scale up production, America could see a substantial decline in infections by the middle of next year. .
Of course, while the good news for America is reason for optimism, we are mindful that the timeline for other countries will vary. Countries will face different timing in terms of access to the vaccines as well as the time it takes to distribute and administer sufficient doses to reach herd immunity.
Still, it is not time to celebrate, at least for the time being. There is still not enough data to tell us whether or not the vaccines coming into the market will prevent transmissions. While we have data on whether people who are vaccinated are less likely to get sick, there is no data on how likely they are to transmit the disease. Transmission rates determine how large a vaccine coverage rate is needed to achieve herd immunity. For example, if a vaccine is 75 percent effective in reducing transmissions, then we need a coverage rate of 60-80 percent for herd immunity. But if it is only 50 percent, a coverage of 90 percent is needed.
Finally, there is the question of how long immunity lasts after being infected. Calculations on coverage change yet again if immunity only lasts for months as opposed to years. Experts believe if immunity is only 6-9 months, then a vaccine coverage rate of around 85 percent is needed to beat the pandemic.
What does all of this mean? While news on the vaccine is good, it is still not absolutely clear when the pandemic shall have been contained. Until we know how effective the vaccines are in reducing transmission rates and how long immunity lasts, we just won’t be able to know how many people in the world need to be vaccinated to achieve herd immunity. The more people who need to be vaccinated, obviously the longer it will take to beat the pandemic.