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Fever Levels Rebound Over Holiday Break

January 4, 2021  ||  kinsa data team

Despite warnings and admonitions to avoid travel and in-person gatherings with friends and family, the Christmas holiday was followed by a noticeable rise in illness associated with the coronavirus.

An analysis of Kinsa’s daily illness indicator showed that fevers had fallen by 14% between Dec. 11 and Dec. 27. However, illness has rebounded: The number of people experiencing fevers in the U.S began increasing two days after Christmas and continued through the New Year, erasing half of December’s progress in just one week. 

This graph shows the dip and rebound in illness around recent holidays

Because people often experience fevers within the first several days of contracting the virus, before they feel sick or get tested, Kinsa’s data is a leading indicator of new virus cases. Often, it takes more than a week or two before these cases are reported by the healthcare system.

This surge comes while hospitals in many areas are at or near capacity. Areas that were already experiencing severe outbreaks in early December are among those that show increases after Christmas. Rhode Island experienced the largest increase in the past week, continuing an upward trend since Dec. 22. New Hampshire, Pennsylvania and Maine saw pronounced increases in illness, along with much of the Northeast. 

A map showing which states saw changes after the holidays

Arizona, California and Texas, all experienced increases in the past week, and have seen some of the highest levels of illness over the past month.  

The recent increase is most pronounced among those over 60, a high-risk group. Older adults also saw the earliest recent increase, trending up starting Dec. 24 and jumping 15% by Jan 2. 

A graph showing the illness trends by age

College-aged and young adults saw an 11% increase last week, similar to other adults 60 and under. But these younger adults, age 18 to 25, had seen the largest recent decrease before the holidays, dropping 30 percent since Dec. 9, around the time that colleges wrapped up classes.

Unfortunately, it seems that Christmas week has followed the trends of previous holidays, likely stalling what would have otherwise been a period of recovery and instead sustaining record case levels in the month ahead.

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