Connect with us

COVID-19

The ‘R factor’ in predicting the spread of COVID-19

Published

on

(Illustration by Viruscorona2020 - Own work + L'épidémie au 02/02/2020 - Pr G Pialoux, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=87803954)

If you’ve been following the news about COVID-19, you may have heard talk about the “R value” or “R factor.”

R0, pronounced “R naught” is a term used in the world of infectious diseases to indicate just how infectious a disease is.

  • If a disease has an R0 of one, it means every infected person will probably infect one person he or she encounters. At that rate, the disease is stable, but a big outbreak or an epidemic is unlikely.
  • An R0 of less than one means each infected person will infect less than one person. In that case, the disease is in decline and will eventually die out.
  • An R0 of more than one means each infected person will infect more than one person and the infection is spreading. If the R0 is three, for example, the probability is that each infected person will infect three others.

Hypothetically, the higher the R0 value, the more likely it is that a disease will spread, potentially causing an epidemic. However, every disease is different, and the R0 really only comes into play when no one in a population has been exposed to the given disease and there is no way to control the spread. That combination of circumstances is rare.

The website Healthline provides the following example:

In 1918 there was a worldwide outbreak of the swine flu (often called the Spanish flu) that killed 50 million people. According to a review article published in BMC Medicine, the R0 value of the 1918 pandemic was estimated to be between 1.4 and 2.8.

But when the swine flu, or H1N1 virus, came back in 2009, its R0 value was between 1.4 and 1.6, report researchers in the journal Science. The existence of vaccines and antiviral drugs made the 2009 outbreak much less deadly.

Researchers have estimated a range of R0 values for COVID-19. In the early days of the pandemic, the value was estimated between 2.2 and 2.7. A July study published online in the journal Emerging Infectious Diseases estimated the value to be much higher at 5.7.

What that means is potentially every infected person can infect another five to six people they contact.

But, as previously stated, R0 is conditional. One condition is the method of transmission. Another factor is the number of people one person encounters. Someone who lives in a crowded city and uses public transportation, or who works in a setting with numerous people, such as a factory assembly line, necessarily will have the opportunity to infect more people. Conversely, a person living and working on a farm in a rural community may only come into contact with his immediate family for extended periods of time. It’s unlikely that the R0 will be the same from one country to another, between states in the same country, or even between metropolitan and rural areas of the same state.

In the U.S. the website Statista.com estimates R0 values range from a low of 0.83 in South Carolina to a high of 1.27 in Wyoming as of Sept. 29. Mississippi is at 0.99. COVID-19 Projections puts it as low as 0.92 for Mississippi. Both values indicate that every infected person will infect fewer than one other person. The same source puts the value at 1.05 for the U.S.

How reliable is R0 as a predictor for the future of COVID-19?

“R0 is notoriously tricky to nail down,” wrote Katarina Zimmer in “Why R0 Is Problematic for Predicting COVID-19 Spread” published in the July/August edition of The Scientist. “It depends not only on the biological characteristics of a virus—which are a mystery at the beginning of an outbreak—but also on understanding how often people come into contact with one another. Faced with uncertainty, modelers have to make assumptions about the factors that determine human movement, which can limit the precision of their models and the accuracy of the predictions they generate.”

Still, R0 is, with few exceptions, the basis for modeling the spread of infectious diseases.

The adage about modeling is that all models are wrong, but some are useful. There are rarely sure things in the world of infectious disease, but having useful information is a step in the right direction. And R0, most scientists agree, is useful, even in a limited way.

COVID-19

Six new COVID-19 cases Tuesday in Warren County; 713 statewide

Published

on

New COVID-19 cases and hospitalizations continue to climb in Mississippi as they have been doing for more than 10 days.

“I do think we are on the front end of something that could be bad,” said State Health Officer Dr. Thomas Dobbs in a Zoom meeting Monday. “The last time we saw that was before the summer surge,” Dobbs added. “That doesn’t mean we can’t turn that around. It’s not that hard. We just have to have a little bit of patience.”

The Mississippi State Department of Health reported six new COVID-19 cases Tuesday in Warren County and no new deaths. The cumulative number of cases in Warren County to date is 1,476, and the county’s death toll is 53.

Statewide, MSDH reported 713 new COVID-19 cases Tuesday, bringing the total cumulative confirmed cases in Mississippi to 105,941. The seven-day average of new cases is 609, higher by 183 cases from a month ago.

Most new cases are seen in younger people recently, and they are more likely to survive the virus than those 65 and older. By far, the age group reporting the most cases in Mississippi are young people from 18 to 29 years old.

MSDH reported Tuesday that 14 additional Mississippians died of COVID-19 statewide. The cumulative number of deaths in the state is 3,115. The state’s rate of deaths to confirmed cases is about 2.9%.

Deaths are a lagging indicator. While July saw the highest number of new cases since the crisis began, August saw the highest number of deaths. The highest number of deaths in any one day was 67 reported Aug. 25.

MSDH reported Tuesday that 13 deaths occurred in the following counties:

County Deaths reported Tuesday
Amite 2
Hancock 1
Harrison 1
Lee 1
Lowndes 1
Marshall 1
Monroe 1
Rankin 1
Tishomingo 1
Washington 3

One COVID-19 related death occurred Sept. 25 in Adams County and was identified from a death certificate report.

New cases and deaths were reported to MSDH as of 6 p.m. Monday, Oct. 12. MSDH usually reports statistics on the COVID-19 coronavirus each day based on the previous day’s testing and death reports.

The primary metric concerning state health officials are the numbers of people hospitalized, and that number rose steadily with the rise of new cases in July and August. On June 6, the number of Mississippians hospitalized with confirmed cases of COVID-19 was at 358. Hospitalizations nearly tripled by late July. They leveled off in early August and began noticeably dropping in the middle of the month including critical cases and numbers of people requiring ventilators. Hospitalizations continued to drop in September but levelled off at the middle of the month. They continued to drop through Oct. 3; however, hospitalizations have been showing a definite rise since then.

The number of Mississippians hospitalized for the virus as of 6 p.m. Monday, Oct. 12, is 600, about half of the late July peak of more than 1,200. The number includes 507 with confirmed cases of COVID-19 and 93 people with suspected but unconfirmed cases. Of those with confirmed infections, 145 were critically ill and in intensive care units and 69 were on ventilators.

Source: MSDH

MSDH has estimated the number of people who can be presumed recovered from COVID-19 in Mississippi. That number is 94,165 through Sunday, Oct. 11. This figure is updated weekly. It represents about 89% of the cumulative 105,941 cases reported Tuesday, Oct. 13.

The number of cases in Warren County three weeks ago, Tuesday, Sept. 22, was 1,382, therefore the estimated number of people presumed recovered in the county is 1,329, or about 90% of the 1,476 cumulative cases reported as of Tuesday, Oct. 11. The county has an estimated 87 active cases.

These estimates are based on MSDH’s guidelines for calculating estimated recoveries when hospitalizations are not known, using the number of cases 21 days ago, less known outcomes (deaths).

The total number of Mississippians tested for COVID-19 (PCR and antigen tests identifying current infections) as of Sunday, Oct. 3, is 863,957 or about 29% of the state’s 2.976 million residents. The positivity rate (positive results to tests, seven-day average) was 6.3% Sunday according to Johns Hopkins University. The national rate is 5%, and 5% or lower indicates adequate testing.

The total number of outbreaks in long-term care facilities is 128 Tuesday. About 40.6%, or 1,265, of the state’s total deaths were people in long-term care facilities.

A total of 25 deaths in Warren County were residents of LTC facilities.

MSDH is no longer reporting outbreaks in individual long-term care facilities in Mississippi and has replaced it with access to a database from the Centers for Medicare and Medicaid. You can access and search the data here. The latest data available is for the week ending Sept. 27.

For additional information, visit the MSDH website.

Continue Reading

COVID-19

Mississippi’s seven-day average for new COVID-19 cases remains over 600 Monday

Published

on

Sunday and Monday saw the expected weekend drop in reported new COVID-19 cases and deaths. Mississippi’s seven-day average remains above 600.

The Mississippi State Department of Health reported three new COVID-19 cases Sunday in Warren County and no new cases Monday. No new deaths were reported either day. The cumulative number of cases in Warren County to date is 1,470, and the county’s death toll is 53.

Statewide, MSDH reported 294 new COVID-19 cases Sunday and 296 cases Monday, bringing the total cumulative confirmed cases in Mississippi to 105,228. The seven-day average of new cases is 646, higher by 197 cases from a month ago.

Most new cases are seen in younger people recently, and they are more likely to survive the virus than those 65 and older. By far, the age group reporting the most cases in Mississippi are young people from 18 to 29 years old.

MSDH reported Sunday that five additional Mississippians died of COVID-19 statewide. No new deaths were reported Monday. The cumulative number of deaths in the state is 3,101. The state’s rate of deaths to confirmed cases is about 3%.

Deaths are a lagging indicator. While July saw the highest number of new cases since the crisis began, August saw the highest number of deaths. The highest number of deaths in any one day was 67 reported Aug. 25.

MSDH reported Sunday that five deaths occurred between Oct. 5 and Oct. 10 in the following counties:

County Deaths reported Sunday
Lafayette 1
Leflore 1
Marion 1
Montgomery 1
Tate 1

New cases and deaths were reported to MSDH as of 6 p.m. Saturday, Oct. 10, and Sunday, Oct. 11. MSDH usually reports statistics on the COVID-19 coronavirus each day based on the previous day’s testing and death reports.

The primary metric concerning state health officials are the numbers of people hospitalized, and that number rose steadily with the rise of new cases in July and August. On June 6, the number of Mississippians hospitalized with confirmed cases of COVID-19 was at 358. Hospitalizations nearly tripled by late July. They leveled off in early August and began noticeably dropping in the middle of the month including critical cases and numbers of people requiring ventilators. Hospitalizations continued to drop in September but levelled off at the middle of the month. They continued to drop through Oct. 3; however, they began showing a definite rise last week.

The number of Mississippians hospitalized for the virus as of 6 p.m. Thursday, Oct. 9, is 600, about half of the late July peak of more than 1,200. The number includes 491 with confirmed cases of COVID-19 and 109 people with suspected but unconfirmed cases. Of those with confirmed infections, 136 were critically ill and in intensive care units and 59 were on ventilators.

Source: MSDH

MSDH has estimated the number of people who can be presumed recovered from COVID-19 in Mississippi. That number is 90,577 through Sunday, Oct. 4. This figure is updated weekly. It represents about 86% of the cumulative 105,228 cases reported Monday, Oct. 11.

The number of cases in Warren County three weeks ago, Monday, Sept. 21, was 1,381, therefore the estimated number of people presumed recovered in the county is 1,328, or about 90.3% of the 1,470 cumulative cases reported as of Monday, Oct. 11. The county has an estimated 89 active cases.

These estimates are based on MSDH’s guidelines for calculating estimated recoveries when hospitalizations are not known, using the number of cases 21 days ago, less known outcomes (deaths).

The total number of Mississippians tested for COVID-19 (PCR and antigen tests identifying current infections) as of Sunday, Oct. 3, is 863,957 or about 29% of the state’s 2.976 million residents. The positivity rate (positive results to tests, seven-day average) was 6.3% Sunday according to Johns Hopkins University. The national rate is 5%, and 5% or lower indicates adequate testing.

The total number of outbreaks in long-term care facilities is 126 Monday. About 40.1%, or 1,258, of the state’s total deaths were people in long-term care facilities.

A total of 25 deaths in Warren County were residents of LTC facilities.

MSDH is no longer reporting outbreaks in individual long-term care facilities in Mississippi and has replaced it with access to a database from the Centers for Medicare and Medicaid. You can access and search the data here. The latest data available is for the week ending Sept. 27.

For additional information, visit the MSDH website.

Continue Reading

COVID-19

Third spike in COVID-19 cases reported Saturday; seven-day average over 600

Published

on

With another spike of new COVID-19 cases Saturday, the third in a week, Mississippi’s seven-day average was above 600 for the first time in over a month, further indicating the state may be seeing the beginning of a new surge in cases. Hospitalizations have also continued to rise throughout the week.

The Mississippi State Department of Health reported eight new COVID-19 cases in Warren County Saturday and no new deaths. The cumulative number of cases in Warren County to date is 1,467, and the county’s death toll is 53.

Statewide, MSDH reported 957 new COVID-19 cases Saturday, bringing the total cumulative confirmed cases in Mississippi to 104,638. The seven-day average of new cases is 638, higher by 180 cases from a month ago.

Most new cases are seen in younger people recently, and they are more likely to survive the virus than those 65 and older. By far, the age group reporting the most cases in Mississippi are young people from 18 to 29 years old.

MSDH reported Saturday that 16 additional Mississippians died of COVID-19 statewide. The cumulative number of deaths in the state is 3,096. The state’s rate of deaths to confirmed cases is about 3%.

Deaths are a lagging indicator. While July saw the highest number of new cases since the crisis began, August saw the highest number of deaths. The highest number of deaths in any one day was 67 reported Aug. 25.

MSDH reported Saturday that 10 deaths occurred between Sept. 23 and Oct. 9 in the following counties:

County Deaths reported Saturday
Alcorn 1
George 1
Hancock 1
Montgomery 1
Panola 1
Stone 1
Tippah 1
Washington 2
Winston 1

Six COVID-19 related deaths occurred between Sept. 25 and Oct. 1 and were identified from death certificate reports.

County Deaths identified on death certificate reports
Desoto 1
Hinds 1
Lee 1
Madison 1
Panola 1
Scott 1

New cases and deaths were reported to MSDH as of 6 p.m. Friday, Oct. 9. MSDH usually reports statistics on the COVID-19 coronavirus each day based on the previous day’s testing and death reports.

The primary metric concerning state health officials are the numbers of people hospitalized, and that number rose steadily with the rise of new cases in July and August. On June 6, the number of Mississippians hospitalized with confirmed cases of COVID-19 was at 358. Hospitalizations nearly tripled by late July. They leveled off in early August and began noticeably dropping in the middle of the month including critical cases and numbers of people requiring ventilators. Hospitalizations continued to drop in September but levelled off at the middle of the month. They continued to drop through Oct. 3; however, they have shown a definite rise this week.

The number of Mississippians hospitalized for the virus as of 6 p.m. Thursday, Oct. 9, is 600, about half of the late July peak of more than 1,200. The number includes 491 with confirmed cases of COVID-19 and 109 people with suspected but unconfirmed cases. Of those with confirmed infections, 136 were critically ill and in intensive care units and 59 were on ventilators.

Source: MSDH

MSDH has estimated the number of people who can be presumed recovered from COVID-19 in Mississippi. That number is 90,577 through Sunday, Oct. 4. This figure is updated weekly. It represents about 86.6% of the cumulative 104,638 cases reported Saturday, Oct. 10.

The number of cases in Warren County three weeks ago, Saturday, Sept. 19, was 1,380, therefore the estimated number of people presumed recovered in the county is 1,327, or about 90.5% of the 1,467 cumulative cases reported as of Saturday, Oct. 10. The county has an estimated 87 active cases.

These estimates are based on MSDH’s guidelines for calculating estimated recoveries when hospitalizations are not known, using the number of cases 21 days ago, less known outcomes (deaths).

The total number of Mississippians tested for COVID-19 (PCR and antigen tests identifying current infections) as of Saturday, Oct. 3, is 863,957 or about 29% of the state’s 2.976 million residents. The positivity rate (positive results to tests, seven-day average) was 5.9% Friday according to Johns Hopkins University. The national rate is 4.9%, and 5% or lower indicates adequate testing.

The total number of outbreaks in long-term care facilities is 126 Saturday. About 40.5%, or 1,254, of the state’s total deaths were people in long-term care facilities.

A total of 25 deaths in Warren County were residents of LTC facilities.

MSDH is no longer reporting outbreaks in individual long-term care facilities in Mississippi and has replaced it with access to a database from the Centers for Medicare and Medicaid. You can access and search the data here. The latest data available is for the week ending Sept. 27.

For additional information, visit the MSDH website.

Continue Reading

Trending