Although vaccines are highly effective in preventing COVID-19, reports of breakthrough infections and new guidelines on mask wearing for vaccinated individuals have caused confusion and concern. Recent studies have shown that vaccinated individuals can still get infected and carry high levels of the virus, but these cases are rare compared to the unvaccinated population. It is important to remember that being vaccinated is crucial in protecting yourself and others. While there is more freedom for vaccinated individuals, it is not the same as before the pandemic. It is also important to note that no vaccine provides 100 percent protection, so it is still necessary to be cautious, especially with the Delta variant. Erin Bromage, a biology professor at the University of Massachusetts, Dartmouth, compares vaccine antibodies to a sea wall that protects a town from a storm surge. While most of the time the wall holds up against waves, a strong hurricane like Delta can allow some water to seep through. Delta is more infectious than earlier forms of the virus, posing a bigger challenge even to vaccinated people. Vaccinations provide extra protection, but may not always hold up against significant challenges, such as being near an unvaccinated person with a high viral load. Despite this, current vaccines in the US are effectively preventing serious illness, hospitalization, and death. Over 97 percent of COVID-19 hospitalizations are among unvaccinated individuals. Recent data from Singapore indicates that vaccinated patients hospitalized with delta breakthrough infections are less likely to require supplemental oxygen and clear the virus faster than unvaccinated patients. While breakthrough infections receive media attention, they are still rare. Although the CDC no longer tracks all breakthrough cases, about half of states provide some data on such occurrences. The Kaiser Family Foundation has recently examined state-reported data and discovered that breakthrough cases, hospitalizations, and deaths are uncommon occurrences among individuals who have been fully vaccinated against COVID-19. The rate of breakthrough cases among fully vaccinated individuals is less than 1% in all states, with percentages ranging from 0.01% in Connecticut to 0.29% in Alaska. However, many cases of breakthrough infections may go unreported because infected individuals may not exhibit symptoms or may experience mild symptoms that resolve before they seek testing. Dr. Asaf Bitton, executive director of Ariadne Labs at Brigham and Women’s Hospital and the Harvard T.H. Chan School of Public Health, noted that while breakthrough infections are rare, the true level of rarity is unknown without a population-based sample. It is uncertain if many individuals with a mild sore throat for a few days actually had breakthrough cases of COVID-19. The occurrence of breakthrough cases is not a result of the vaccine's failure. It has been estimated that the vaccine campaign has prevented 100,000 to 200,000 deaths. The risk of a breakthrough infection increases when individuals are exposed to the delta variant multiple times, weakening the protection provided by the vaccine. Large events, such as the July 4 celebration in Provincetown, Massachusetts, or the Lollapalooza concert in Chicago, pose a higher risk of vaccinated individuals coming into contact with someone carrying a high viral load. The more people you interact with, the higher the risk, depending on the local risk level. In the near future, there may be a surge in COVID-19 cases at events like Lollapalooza, where large crowds are at high risk for spreading the delta variant. The CDC recommends wearing masks in areas designated as orange or red on their color-coded map, which includes roughly 80 percent of counties in the United States with high infection rates. The Northeast and Upper Midwest have low infection numbers, while states like Missouri, Arkansas, Louisiana, and Florida are experiencing spikes in cases due to the delta variant. It is important to note that case counts are changing quickly, so your local community may see a surge in cases before the map is updated. Even if you live in a highly vaccinated area with low case counts, it is wise to consider the situation in nearby communities as well since people and viruses can easily cross boundaries. Experts generally agree that wearing a mask outdoors is not necessary if you are not in a crowded area and can maintain a distance of at least 6 feet from others whose vaccination status is unknown. However, attending a packed outdoor event is still considered risky, and if you choose to do so, wearing a mask is recommended. "I would recommend continuing to wear a mask indoors around people whose vaccination status is unknown, especially if you will be close to them for an extended period of time," advised J Alex Huffman, an aerosol scientist and associate professor at the University of Denver. "Although I am fully vaccinated and do not always wear a mask indoors, I do wear my N95 mask in indoor public spaces. If you are considering upgrading your mask, high-quality medical masks such as N95 or KN95 offer the best protection, ensuring they are authentic. Another option is a KF94 mask from Korea, known for its quality and lower risk of counterfeits. If you do not have a medical mask, double masking with a surgical mask underneath a cloth mask can provide strong protection." Wearing a mask with an exhale valve is not recommended as it can allow viral particles to escape, and counterfeit masks may have faulty valves that let germs in. It is important to choose the appropriate mask based on the situation. A cloth mask may suffice for a brief visit to a sparsely populated convenience store in a highly vaccinated area, but a higher-quality mask is advisable for air travel or crowded grocery stores, especially in areas with low vaccination rates and high case counts. Masks with straps or ties around the back of the head provide a tighter seal than masks with ear loops. Huffman emphasized the need for enhanced mitigation efforts, particularly when it comes to dealing with the delta variant, including the use of high-quality masks that fit tightly to the face. He advised ensuring that the mask is sealed well all around the edges, over the nose bridge, by the cheeks, and under the chin. According to him, a tightly fitting mask is more effective than a loose-fitting one. Vaccinated individuals have very low risk of contracting the virus when they are with other vaccinated friends and family members without wearing masks, according to Huffman. While wearing masks is not considered critical in indoor gatherings with a small group of vaccinated individuals, extra precautions may be necessary in certain situations. Although it is rare for a vaccinated person to transmit the virus to another vaccinated person, it is still theoretically possible. Those who engage in high-risk activities such as going to crowded events or traveling to COVID hotspots pose a greater risk compared to those who avoid large crowds and primarily spend time with other vaccinated individuals. With the delta variant on the rise, Bitton recommends prioritizing outdoor gatherings, especially for families with unvaccinated members or those at high risk. Moving your event to a backyard or patio and minimizing indoor time can reduce the risk of exposure. Spending time with small groups of vaccinated friends is safer than attending large parties, even if everyone is vaccinated. When indoors, opening windows for better ventilation is advised. For individuals at very high risk, such as the elderly or immunocompromised, it is reasonable to request that even vaccinated individuals get tested before visiting. It is possible to provide guests with a quick home test to ensure they are not infected with COVID-19. Whether or not it is safe to dine at restaurants depends on factors such as local vaccination rates, case counts, personal health, and individual risk tolerance. Dining in a restaurant in Vermont, where two-thirds of the population is vaccinated, is less risky than dining indoors in Alabama or Mississippi, where only one-third of residents are vaccinated. Parents of unvaccinated children and individuals with compromised immune systems, who may not receive as much protection from vaccines according to studies, may choose to order takeout or eat outside as an extra safety measure. Is it advisable to travel? Should I avoid peanuts and water and continue wearing my mask? While airplanes are usually well ventilated and not a significant source of outbreaks, taking precautions is still recommended. The risk of coming into contact with an infected individual may be higher in the airport terminal, while dining at airport restaurants and bars, or going through security. Air on airplanes is replaced every two to three minutes, a faster rate than in grocery stores and other indoor areas. Passengers are allowed to take off their masks to eat or drink, but ventilation systems keep airflow limited to a few rows to prevent it from circulating throughout the entire cabin. Infected passengers pose the greatest risk to those nearby, so experts recommend using high-quality medical masks like N95 or KF94 when flying. If you do not have a mask, it is recommended to wear two masks. For those who are vaccinated, the risk of briefly removing a mask to eat or drink during a flight is low, but it is best to keep it on as much as possible. The CDC advises unvaccinated individuals, including children, to avoid flying. Bromage shared that he recently flew and took his mask off briefly to drink, but kept it on for most of the flight. He mentioned that he would feel more at ease removing his mask to eat if he knew his seatmates were vaccinated. He mentioned that he would be worried if the person next to him was not following COVID precautions or wearing their mask incorrectly. He emphasized the importance of keeping the mask on, especially when around strangers or talkative individuals. Despite being vaccinated, there is still a risk of viral exposure on buses, subways, and trains, as most still require masks to be worn, which helps to reduce the risk. The level of risk depends on factors such as the duration of the ride and the level of crowding on the train or bus. For a lot of individuals, using public transportation is necessary for commuting to work or school, and it is advised to wear a properly fitting medical mask or double mask. When taking public transit is not obligatory, the choice of whether to ride should take into account the vaccination rates in the area and if there is an increase in case numbers. Can I embrace and visit elderly family members? What about children who are not vaccinated? While it is typically deemed safe for vaccinated individuals to hug and socialize without masks, parents of unvaccinated children have more factors to think about, especially when visiting older relatives. In areas where there are few cases of COVID-19 and many people are vaccinated, it is generally considered safe for unvaccinated children from one household to visit vaccinated grandparents. However, with the spread of the delta variant and children returning to school, the risk of close contact increases for older or immunocompromised individuals who are more susceptible to severe illness from COVID-19. When planning a visit to a high-risk family member, it is advisable to limit exposure by avoiding activities such as dining out or going to the gym in the week leading up to the visit. Even though the chances of a vaccinated person transmitting the virus are low, vaccinated grandparents should also minimize their own exposure when spending time with unvaccinated children. Huffman, an aerosol scientist, mentioned that despite not wearing masks indoors with his elderly parents currently, he is still cautious about wearing masks in public places. “If I had more interactions that increased my overall risk of exposure, I would strongly consider wearing a mask when indoors with vulnerable individuals,” said Bromage. Rapid home tests are an additional precaution when visiting grandparents or immune-compromised family members. It is recommended to take a test a few days before the visit as well as on the day of the visit. Home tests are a good option for those who are feeling anxious about the virus. Bromage suggests that everyone take a test right before coming together to ensure that everyone is clear of the virus and can safely enjoy their time together. How can one determine if they have the delta variant? If you are diagnosed with COVID-19 in the United States, it is highly likely that you have the delta variant, according to the CDC. The delta variant is now the most common strain in the US, accounting for over 82 percent of cases. This variant has also become dominant in many other countries, with the World Health Organization reporting that it makes up 75 percent or more of cases in countries such as Australia, Bangladesh, Botswana, China, Denmark, India, Indonesia, Israel, Portugal, Russia, Singapore, South Africa, and the UK. Unfortunately, standard COVID tests cannot determine if your infection is specifically caused by the delta variant or another strain of the virus. Although health departments may utilize genomic sequencing to detect various variants in a population, this data is usually not disclosed to individuals. It is important to continue isolating and consulting with healthcare professionals if experiencing low blood oxygen levels, difficulty breathing, or other concerning symptoms. © 2021 The New York Times Company.