When Will This REALLY be Over? Part 2 of 4: Global Mega Peak

Welcome back friends, In part 1 of this essay series posted on April 21, 2020, I summarized three indicators that will tell us when the coronavirus pandemic is really over. By “really over” I mean we can hug, shake hands, gather in enormous crowds, and travel the world again. When we get to behave as we did in 2019 and do it without fear of inducing skyrocketing COVID-19 cases! First, we discussed the “wait it out” approach. Eventually, regardless of what we do, new COVID-19 cases will decline after we surpass the global mega peak. Second, we discussed the “hunt and catch” approach to test everyone everywhere for coronavirus infection followed by contact tracing. Third, we discussed the “armor and shields” approach involving the global deployment of an effective vaccine or other protective treatment. In this post, I’ll elaborate on the wait it out approach, the concept of a global mega peak and herd immunity. We'll answer these 5 questions: 1) WHAT is the global mega peak? 2) What does SUCCESS look like? 3) What is the status TODAY? 4) What MILESTONES will show progress? 5) WHO is doing this work? 1) WHAT is the global mega peak? By now you are used to seeing COVID-19 case data displayed as curves. In the beginning, there are few cases, but over time the line rises as the virus infects more people. The top of the curve, called the peak or apex, happens when the greatest number of people have the virus. After the peak, cases steadily decline. The phrase “flatten the curve” refers to our efforts to prevent a surge in sickness that could overcrowd our hospitals. Social distancing, wearing masks, staying at home, limiting travel, and hand hygiene helps slow the spread of the virus and “flatten the curve.” When someone shows you data on the curve, which curve are they referring to? It could be one of many curves. Curves for your city. Your county. Your state. Other states. The United States. Or other countries. To know when this pandemic is nearing its natural end, there is only one curve that matters most—the curve for all of humanity. There is only one peak that matters most—the global mega peak. It is formed from the stacking of regional curves. The global mega peak is the point when we will hit record high numbers of new COVID-19 infections in the world’s total. 2) What does SUCCESS look like?

So long as large regions of the globe are still experiencing increasing rates of new coronavirus infections, travel among countries will remain risky. Once the collective coronavirus data for all humans peaks and then declines, though, it will be a sign that the novel coronavirus pandemic is winding down. In response to some (but not all) germs, our immune system can produce antibodies that protect us from getting infected with the same germ a second time. The coronavirus that causes COVID-19 probably does this. Each person who has been infected and recovered from this coronavirus infection should have individual immunity against reinfection. When lots of people develop immunity to a specific germ, it is called herd immunity. Herd immunity against COVID-19 will happen once the virus struggles to find new susceptible people to infect. John Hopkins University reported in an article from April 10, 2020, that we will have herd immunity once approximately 70% of people have recovered from the novel coronavirus (SARS-CoV-2). 3) What is the status TODAY? About 3 million confirmed cases of COVID-19 have been reported in total. This might sound like a lot, but there are approximately 7.6 billion people on earth. Therefore, only 0.04% of the global population has had a confirmed case included in this data set. That means that for every 2500 people on earth, only about 1 person has had a confirmed (more on that later) case of COVID-19, so far. Let’s look at the global data set as of today together. Here is a screenshot from John Hopkins University’s COVID-19 maps page that I took today: COVID-19 Map.

Screenshot taken on April 27, 2020, copyright 2020 Johns Hopkins University, all rights reserved The cases started out relatively low in January and February. Throughout March, the numbers increased most days. So far in April, the numbers are ranging from between about 70,000 to 90,000 new cases per day. We are still seeing a steady increase in new daily cases reported worldwide, but the number of new cases is about the same each day. Therefore, we see a flat curve that is not increasing or decreasing. It is too early to tell whether the leveling-off will start to decline, or if this is just a flat spot on a curve that will soon begin to rise again. Much of the world is actively trying to flatten their local curves. The leveling off seen in April may be evidence of the effect of these actions, rather than evidence of herd immunity. In the next section, we’ll talk about the milestones that will give us knowledge, information, and insights we will need to accurately interpret the trajectory of our global human coronavirus infection curve. 4) What MILESTONES will show progress? There are three milestones, or hurdles, that we need to overcome before we can confidently say that the pandemic is really nearing an end based on an observed decline in the global mega curve. 1) Verify people who previously tested positive are immune to reinfection. 2) Learn approximately how many people had it without being tested. 3) Witness a decline months after we lift curve-flattening restrictions. One milestone that will show progress is to verify that people who previously tested positive for COVID-19 cannot get reinfected. Based on what scientists know so far, most believe this is true. It is unproven, though. There have been reports of people testing positive, recovering, and then testing positive again. However, many experts think these results might be caused by inaccurate test results (e.g. saying they were positive when they were not or vice versa). Experts are not sure whether someone has to feel sick (have symptoms) when they are infected to build up an effective antibody defense. Some people get infected with the virus and never show symptoms. We don’t know if those people will be protected and be part of the herd immunity or not. The second milestone of progress is to estimate how many people were infected but never tested. The data I showed on the John Hopkins graph above only includes cases that tested positive. In most areas of the world, though, only people who are sick enough to need to go to a hospital get tested, and not even all of those do. Many people get sick, but stay home and never get tested. Others never feel sick even when they are infected. This data is missing from our global curve. We won’t be able to make accurate interpretations of the global curve until we fill in the missing data. Fortunately, people are working on deploying tests that look for evidence of past infection by testing blood for antibodies against the novel virus. The results, even if they are collected in only parts of the world, will give us better estimates of how many people have been exposed, but aren’t yet included in the data reported today. If the number is higher than expected, that will be good news. It will mean that we are closer to the end. If the number is low, then it means most of us are still vulnerable and it will take longer to see the decline in global new cases. A third milestone showing progress is a decline in new cases globally for months after curve-flattening behaviors subside. Everything everyone is doing all over the world to prevent the spread of COVID-19 affects the global curve. It might stay flat, and possibly dip, even if everyone continues to avoid travel and crowds while practicing great hygiene. For this pandemic to really be over, though, we’ll need to see the virus not flare up once we return to normal behaviors. Data so far has shown that curves flatten about a month after we start curve-flattening activities. We’ll want to wait at least two months after we lift restrictions globally to verify that cases don't bounce back up. If they don’t, then that is great news and will be evidence that herd immunity is here. As we monitor the global curve, we need to remember the data we are looking at today is not complete. We must verify immunity after infection, estimate how many cases are untested, and see the decline sustain even after we return to life-as-usual. We need to gather this missing information before we can know for sure if the pandemic is coming to its natural end. 5) WHO is doing this work? The World Health Organization (WHO) is primarily responsible for collecting and sharing data from individual countries and regions. You can view graphs and maps of this data on their website. In addition, John Hopkins University displays world data from the WHO reporting and even more detail on the United States data. Their COVID-19 graphs and maps are located here. If you read my second post, you might remember that I talked about how important it is to include a global perspective when you are getting your COVID-19 news. Well, visiting these sites to get the current data on the global human curve is a great place to start your proactive coronavirus news updates. I’ll be back next time with a more detailed discussion about testing and contact tracing. Take care, COVID Carrie