What are the markers of a second COVID-19 wave?
What are the markers of a second COVID-19 wave?
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There is no single definition of a “wave” of a disease in public health. Defining a disease wave varies across scientific literature and even by the scientist you ask. This lack of continuity has to do with the complexity of disease outbreaks, and in particular 1) the ways in which diseases affect different populations at different times, 2) the difficulty in accessing accurate data, and 3) most importantly, the lack of a standardized definition of a disease wave. We do, however, know a disease wave when we see one in public health, and agree on indicators of second, third, and fourth waves, and beyond. A disease wave can be thought of as a sustained surge (or spike) in cases, following and relative to a period of sustained low cases. Think of a line on a graph that curves high (first wave), dips low (end of the first wave), then curves high again (second wave). In defining the end of a first wave for the U.S., on June 18 2020, Dr. Anthony Fauci, U.S. White House advisor and director of the National Institute of Allergy and Infectious Diseases, told the Washington Post that in order to consider the first wave in the U.S. technically "over", we would need to see a specific region, state, or city have a sustained decrease of positive infection rates until they were in the low single digits. This is just one expert's definition, however, and just because a region may not have reached single digits of positive test rates does not mean they might not be considered by some to be in a second wave now, and by others in a third wave, if they’re seeing a significant and sustained surge in positive rates compared to what that area’s positive test rate number was previously.
There is no single definition of a “wave” of a disease in public health. Defining a disease wave varies across scientific literature and even by the scientist you ask. This lack of continuity has to do with the complexity of disease outbreaks, and in particular 1) the ways in which diseases affect different populations at different times, 2) the difficulty in accessing accurate data, and 3) most importantly, the lack of a standardized definition of a disease wave. We do, however, know a disease wave when we see one in public health, and agree on indicators of second, third, and fourth waves, and beyond. A disease wave can be thought of as a sustained surge (or spike) in cases, following and relative to a period of sustained low cases. Think of a line on a graph that curves high (first wave), dips low (end of the first wave), then curves high again (second wave). In defining the end of a first wave for the U.S., on June 18 2020, Dr. Anthony Fauci, U.S. White House advisor and director of the National Institute of Allergy and Infectious Diseases, told the Washington Post that in order to consider the first wave in the U.S. technically "over", we would need to see a specific region, state, or city have a sustained decrease of positive infection rates until they were in the low single digits. This is just one expert's definition, however, and just because a region may not have reached single digits of positive test rates does not mean they might not be considered by some to be in a second wave now, and by others in a third wave, if they’re seeing a significant and sustained surge in positive rates compared to what that area’s positive test rate number was previously.
Publication
What our experts say
There is no single definition of a “wave” of a disease in public health. Defining a disease wave varies across scientific literature and even by the scientist you ask. This lack of continuity has to do with the complexity of disease outbreaks, and in particular 1) the ways in which diseases affect different populations at different times, 2) the difficulty in accessing accurate data, and 3) most importantly, the lack of a standardized definition of a disease wave.
We do, however, know a disease wave when we see one in public health, and agree on indicators of second, third, and fourth waves, and beyond. A disease wave can be thought of as a sustained surge (or spike) in cases, following and relative to a period of sustained low cases. Think of a line on a graph that curves high (first wave), dips low (end of the first wave), then curves high again (second wave).
In defining the end of a first wave for the U.S., on June 18 2020, Dr. Anthony Fauci, U.S. White House advisor and director of the National Institute of Allergy and Infectious Diseases, told the Washington Post that in order to consider the first wave in the U.S. technically "over", we would need to see a specific region, state, or city have a sustained decrease of positive infection rates until they were in the low single digits.
This is just one expert's definition, however, and just because a region may not have reached single digits of positive test rates does not mean they might not be considered by some to be in a second wave now, and by others in a third wave, if they’re seeing a significant and sustained surge in positive rates compared to what that area’s positive test rate number was previously.
There is no single definition of a “wave” of a disease in public health. Defining a disease wave varies across scientific literature and even by the scientist you ask. This lack of continuity has to do with the complexity of disease outbreaks, and in particular 1) the ways in which diseases affect different populations at different times, 2) the difficulty in accessing accurate data, and 3) most importantly, the lack of a standardized definition of a disease wave.
We do, however, know a disease wave when we see one in public health, and agree on indicators of second, third, and fourth waves, and beyond. A disease wave can be thought of as a sustained surge (or spike) in cases, following and relative to a period of sustained low cases. Think of a line on a graph that curves high (first wave), dips low (end of the first wave), then curves high again (second wave).
In defining the end of a first wave for the U.S., on June 18 2020, Dr. Anthony Fauci, U.S. White House advisor and director of the National Institute of Allergy and Infectious Diseases, told the Washington Post that in order to consider the first wave in the U.S. technically "over", we would need to see a specific region, state, or city have a sustained decrease of positive infection rates until they were in the low single digits.
This is just one expert's definition, however, and just because a region may not have reached single digits of positive test rates does not mean they might not be considered by some to be in a second wave now, and by others in a third wave, if they’re seeing a significant and sustained surge in positive rates compared to what that area’s positive test rate number was previously.
Context and background
Talk of a second wave has been heavily underway since early to mid-summer, when cases of COVID-19 started to stay consistent or fall in some cities, particularly those that were hit hardest and therefore had the most thorough initial response plans. At the time, we were still firmly in the first wave, which most media outlets accurately explained.
Media attention regarding second and third waves of COVID-19 globally has resumed, with cases of COVID-19 surging following lower numbers of cases in the late spring and over the summer on average in the U.S. and in many parts of the world, such as the Spain and Iceland. In the U.S., some experts argue that we are still in the second wave, with the projection that it will peak (hit its highest number of cases) in mid-late November. Other experts argue that we are in a third wave based on how cases have dropped twice and are now surging a third time. Again, these different perspectives are based on different definitions of disease waves. Regardless of which wave we're in, the U.S. and many parts of the world are experiencing a surge in cases that is projected to worsen. The timing of this surge is especially challenging given its overlap with other respiratory viruses such as influenza.
Talk of a second wave has been heavily underway since early to mid-summer, when cases of COVID-19 started to stay consistent or fall in some cities, particularly those that were hit hardest and therefore had the most thorough initial response plans. At the time, we were still firmly in the first wave, which most media outlets accurately explained.
Media attention regarding second and third waves of COVID-19 globally has resumed, with cases of COVID-19 surging following lower numbers of cases in the late spring and over the summer on average in the U.S. and in many parts of the world, such as the Spain and Iceland. In the U.S., some experts argue that we are still in the second wave, with the projection that it will peak (hit its highest number of cases) in mid-late November. Other experts argue that we are in a third wave based on how cases have dropped twice and are now surging a third time. Again, these different perspectives are based on different definitions of disease waves. Regardless of which wave we're in, the U.S. and many parts of the world are experiencing a surge in cases that is projected to worsen. The timing of this surge is especially challenging given its overlap with other respiratory viruses such as influenza.
Resources
- Explainer: What is a second wave of a pandemic, and has it arrived in the U.S.? (Reuters)
- What a ‘second wave’ of Covid-19 could look like and how to prevent it (CNBC)
- Anthony S. Fauci: ‘We are still in the first wave’ of coronavirus (Washington Post)
- First and Second Waves of Coronavirus (Johns Hopkins Medicine)
- Second wave COVID-19 pandemics in Europe: a temporal playbook (Nature)
- Experts project autumn surge in coronavirus cases, with a peak after Election Day (Washington Post)
- U.S. Virus Cases Climb Toward a Third Peak (NYT)
- Explainer: What is a second wave of a pandemic, and has it arrived in the U.S.? (Reuters)
- What a ‘second wave’ of Covid-19 could look like and how to prevent it (CNBC)
- Anthony S. Fauci: ‘We are still in the first wave’ of coronavirus (Washington Post)
- First and Second Waves of Coronavirus (Johns Hopkins Medicine)
- Second wave COVID-19 pandemics in Europe: a temporal playbook (Nature)
- Experts project autumn surge in coronavirus cases, with a peak after Election Day (Washington Post)
- U.S. Virus Cases Climb Toward a Third Peak (NYT)
