Q: How many people need to use exposure notification for it work?
Q: Will exposure notification apps be useful for anything post-pandemic?
A: At some point in 2021, most people are going to have either been vaccinated, or have been infected naturally with SARS-CoV-2. But achieving this “herd immunity” won’t get rid of the virus altogether. No vaccine provides 100% protection, and even good immunity wanes over time. Some people will get infected despite their vaccination or prior infection. Newborn babies will also keep providing a new source of humans for the virus to infect. And new strains of the virus are emerging that “escape” our prior immunity to reinfect us at much higher rates. We can expect COVID-19 to becoming “endemic”, meaning it is not going away.
Nevertheless, things will get a lot better. While the virus will keep circulating, we hope that when you catch it the second time, or catch it after being vaccinated, it will just be a common cold, like other endemic human coronaviruses. Or perhaps it will be worse, more like influenza. Or perhaps it will be somewhat worse than influenza, but still not nearly as bad as it is now.
Is this good enough? People forget how bad influenza is - it causes between 9 million – 45 million illnesses, between 140,000 – 810,000 hospitalizations and between 12,000 – 61,000 deaths per year in the US. Public health has long been underappreciated and underfunded, and while flu vaccines are now readily available (albeit not very effective ones), there has never been a serious attempt to use a test, trace, and isolate strategy for influenza. Might this pandemic be the turning point, where we realize that with sufficient will, we can do better? Is it time to stop seeing influenza as inevitable, and start fighting it using the tools we have developed to fight COVID-19, including mRNA vaccines, extensive testing, and both manual and digital contact tracing?
I like to think that at least some good things might come out of all the suffering of this pandemic. Let’s plan to save future influenza victims, at the same time also preparing for a long fight against endemic COVID-19, should it turn out to be less like a common cold and more like influenza. What is more, having a more robust public health system capable of fighting influenza will help us nip future pandemics in the bud.
What do I mean by “fighting” influenza or COVID-19? We aren’t likely to get rid of either of these diseases altogether, the way we eliminated smallpox. Even if some countries manage, they will keep getting re-introduced from other countries. But we can contain these diseases through widespread testing and isolation and tracing and quarantine. This would be in addition to vaccination, which probably won’t be enough on its own, given how COVID-19 evolves to escape past immunity. Like measles, the disease wouldn’t go away altogether, but it would be kept at bay. And when outbreaks occur, we will move quickly to squelch them.
A gentler alternative to containment is mitigation. Quarantine is hard on people. One gentler option is to test and trace influenza and endemic COVID-19, but then instead of recommending strict 14 day quarantine, to aim for less dramatic behavior change. Both influenza and COVID-19 are most dangerous to the elderly - what if we just stayed away from the vulnerable on certain days, instead of staying home completely? Imagine an exposure notification app in 2022 that tells you about both SARS-CoV-2 and influenza exposures, and that warns you not to visit your grandfather and to take quarantine leave from your job in a nursing home or hospital. That would save a lot of lives, even if it doesn’t make these viruses go away.
Google and Apple plan to switch the exposure notification system off after the pandemic. They are looking to the CDC and WHO to help define when the system is no longer needed because the pandemic is over. But how many deaths per year are too many? Is the burden from influenza acceptable, now that we know we have tools that could substantially reduce it? We suspect that the system will not, in fact, be turned off, and if it does we can fall back on the technology we built to continue to provide exposure notifications outside the API currently provided by Google and Apple. Exposure notification apps are for the first time giving public health authorities a powerful tool on citizens’ phones, capable of providing critical advice at just the time it is needed, in terms that are easy to understand. WeHealth will support its public health clients in using this or similar tools to make us healthier, including the fights against outbreaks of previously controlled diseases such as measles and pertussis, as well as COVID-19 and influenza.
Have a question? Ask the professor: contact@wehealth.org
