12 November 2024

8 minute read

By: University of Pennsylvania

North America

With bird flu virus detected in cow’s milk, U.S. health authorities have warned the public against potential sources of exposure, including drinking raw or unpasteurized milk, and have reiterated a general warning that consuming uncooked or undercooked poultry or beef products can make you sick.

Relatively few people say they drink raw milk. Only 3% of US adults report having consumed raw milk in the past 12 months, while 4% were not sure whether they had, according to a new nationally representative Annenberg Public Policy Center health survey of nearly 1,500 empaneled US adults conducted in July.*

But many more people say they do not use a food thermometer to ensure that their food is heated to a temperature high enough to kill bacteria and viruses, including avian influenza A viruses like the H5N1 strain now found in US cattle. And most are unsure what internal food temperatures kill bacteria and viruses, according to the survey.

Using a food thermometer

Only about 1 in 4 US adults (27%) report using a food thermometer either “often” or “all the time” to check whether the meat, poultry, or fish they consume has reached an internal temperature that makes the food safe to eat. A similar proportion (29%) say they “never” use a food thermometer to check temperatures while 20% say they do “rarely” and 20% “sometimes.”

“Using a food thermometer to determine that meat, poultry, fish, and eggs have been cooked to a safe internal temperature, one that kills bacteria such as E. coli and salmonella, is a way of protecting yourself from food poisoning,” said Kathleen Hall Jamieson, director of the Annenberg Public Policy Center (APPC) of the University of Pennsylvania. “Every cook should have a food thermometer within ready reach in the kitchen or near the grill.”

The data come from the 20^th wave of a nationally representative panel of 1,496 U.S. adults, conducted for the Annenberg Public Policy Center by SSRS, an independent market research company. This wave of the Annenberg Science and Public Health (ASAPH) Knowledge survey was fielded July 2024 and has a margin of sampling error (MOE) of ± 3.6 percentage points at the 95% confidence level. See the topline and methodology for details.

Food temperature and killing viruses such as bird flu

According to the Centers for Disease Control and Prevention (CDC), “While there is no evidence that anyone in the United States has gotten infected with avian influenza A viruses after eating properly handled and cooked poultry products, uncooked poultry and poultry products (like blood) could have been the source of a small number of avian influenza A virus infections in people in Southeast Asia.” 

The USDA reported in May as part of testing of 96 dairy cows that the virus had been detected in the meat of one “cull” cow but it did not enter the food chain and the USDA is confident that the meat supply is safe: “While we have multiple safeguards in place to protect consumers, we continue to recommend consumers properly handle raw meats and cook to a safe internal temperature.”

The APPC survey finds that most US adults do not know the correct temperatures to heat food to in order to kill the H5N1 virus, or bird flu. Thinking about the virus, the survey respondents were asked to indicate which of the measures below “will kill the H5N1 virus,” and to select all that apply. Over half of those surveyed (51%) indicated “not sure” on this item and 4% incorrectly said “none will kill”:

• Heating poultry to at least 165 degrees Fahrenheit (CORRECT): Fewer than 4 in 10 (38%) selected this option as correct. According to the CDC, cooking poultry and eggs to an internal temperature of 165 degrees kills bacteria and viruses, including H5N1.
• Heating ground beef to at least 165 degrees Fahrenheit (CORRECT): This is true, but less than 1 in 3 people surveyed (29%) selected it. (In fact, the CDC recommends heating ground beef to at least 160 degrees.)
• Heating steak to a least 145 degrees (CORRECT): Just over 1 in 5 (21%) selected this as correct. According to the CDC, whole cuts of beef should be heated to 145 degrees then allowed to rest for three minutes.
• Freezing beef to a temperature of at least 20 degrees Fahrenheit (INCORRECT): Only 7% chose this thinking it is correct (it is not). Bird flu survives indefinitely while frozen and remains infectious, according to the Occupational Safety and Health Administration.
• Heating beef to at least 120 degrees (INCORRECT): Only 10% chose this, but it is not correct.

The bird flu outbreak

Unpasteurized or raw milk comes from animals including cows, sheep, and goats, and it has not been pasteurized to kill harmful germs. Unpasteurized dairy products are estimated to “cause 840 times more illnesses and 45 times more hospitalizations than pasteurized products.” The CDC says that consuming unpasteurized milk and products made from it “can expose people to germs such as Campylobacter, Cryptosporidium, E. coli, Listeria, Brucella, and Salmonella.”

In fact, 171 people were sickened and 22 hospitalized from September 2023 to March 2024 in a salmonella outbreak connected to unpasteurized milk from Raw Farm, in Fresno, Calif., according to the New York Times, which said this is the largest recorded outbreak in over two decades linked to raw milk.

In June, the FDA reported in an open letter that bird flu, or the H5N1 avian influenza virus, has been detected in cow’s milk. The presence of H5N1 bird flu was confirmed in cattle in the United States in mid-March 2024. As of July 25, 2024, there had been 13 human cases of bird flu in the United States since April 2024, four following exposure to cows and nine following exposure to poultry in Colorado. As of mid-July, 168 cattle herds in 13 states – and over 100 million poultry in 48 states – were affected.

Raw milk and bird flu

As of mid-June 2024, the FDA concluded “that the totality of evidence continues to indicate that the commercial milk supply [which is pasteurized] is safe.” The FDA says it does not currently know whether the H5N1 virus can be transmitted to humans through consumption of raw milk products from infected cows, though a study with mice concluded that the virus in “untreated milk can infect susceptible animals that consume it” and the National Institutes of Health (NIH) says this suggests that drinking raw milk “may pose a risk of transmission to people.”

The Annenberg survey finds that 15% of respondents think drinking raw milk increases the chances of getting bird flu, while 33% think it has no effect one way or the other on the chances of getting bird flu. Nearly half of those surveyed (49%) are not sure.

Pasteurization and the risks of raw milk

According to the CDC, pasteurization “is crucial for milk safety, killing harmful germs that can cause illness” and the NIH says “dairy milk purchased in the grocery store has been pasteurized – heated to a level high enough and long enough to kill most viruses or bacteria in the milk.”

Yet the current survey shows just over half of those surveyed (54%) know that unpasteurized milk is less safe to drink than pasteurized milk. While 6% say raw milk is safer to drink and 13% say it is just as safe, 27% say they are not sure which is safer.

The survey also finds that:

• Bacteria and viruses: 62% think it is likely that raw milk contains bacteria and viruses that can make you sick, while 16% say it is unlikely and 22% are not sure.
• Effectiveness of pasteurization: 77% know pasteurization is effective at killing bacteria and viruses in raw milk, while 4% say it is not effective and 20% are not sure.
• Nutrients: Over a quarter of those surveyed (26%) say raw milk has more nutrients than pasteurized milk, 30% think it has “about the same amount of nutrients as pasteurized milk,” and 40% are not sure.

While those who advocate for drinking raw milk contend that pasteurization destroys valuable nutrients, the FDA says that raw milk “is not nutritionally superior” to pasteurized milk.

Bird flu and the seasonal flu vaccine

Nearly two-thirds of those surveyed do not know that the seasonal flu vaccine will not help prevent bird flu – 21% think it does help a person who is exposed to the H5N1 bird flu from developing severe illness and 44% are not sure whether it does. Just over a third of those surveyed (35%) know that the seasonal flu vaccine does not help someone exposed to bird flu from developing severe illness.

APPC’s ASAPH survey

The survey data come from the 20^th wave of a nationally representative panel of 1,496 U.S. adults, first empaneled in April 2021, conducted for the Annenberg Public Policy Center by SSRS, an independent market research company. This wave of the Annenberg Science and Public Health Knowledge (ASAPH) survey was fielded July 11-18, 2024, and has a margin of sampling error (MOE) of ± 3.6 percentage points at the 95% confidence level. All figures are rounded to the nearest whole number and may not add to 100%. Combined subcategories may not add to totals in the topline and text due to rounding.

See the topline and methodology for additional details.

The policy center has been tracking the American public’s knowledge, beliefs, and behaviors regarding vaccination, Covid-19, flu, maternal health, climate change, and other consequential health issues through this Annenberg Science and Public Health (ASAPH) survey panel for over three years. In addition to Jamieson, the APPC team includes senior data analyst Laura Gibson; research analyst Shawn Patterson Jr.; Patrick E. Jamieson, director of the Annenberg Health and Risk Communication Institute, who developed the questions; and Ken Winneg, managing director of survey research.

* The percentage of raw milk drinkers found in the APPC survey, which included non-milk drinkers, is roughly consistent with a Food and Drug Administration (FDA) 2016 food safety report finding that 4% of U.S. adults who drink milk reported having had raw milk over the prior 12 months. Unlike the FDA survey, the APPC survey gave people the explicit option of indicating that they were not sure.