Question: What has the CDC done to stop shipboard outbreaks?

Answer passage (source: CDC):
page_title: CDCâs role in helping cruise ship travelers during the COVID-19 pandemic
section_content: Outbreaks of infectious diseases can happen on cruise ships because people
spend time close together and with travelers from many countries. Disease can
spread between ships when crew members from a ship with an outbreak transfer
to other ships. Infected people may also travel on cruise ships between
countries. For these reasons, outbreaks of COVID-19 on cruise ships pose a
risk for rapid spread of disease beyond the voyage and into communities across
the globe.
Because of the unprecedented nature of the COVID-19 pandemic and the high risk
of COVID-19 spread on cruise ships, the US government issued a No Sail Order
for cruise ships in waters subject to US jurisdiction and has advised US
travelers to defer all cruise
travel.
The No Sail Order is published in the Federal
Register.
CDC continues to work to control COVID-19 on cruise ships at sea while also
protecting against further introduction and spread of COVID-19 into
communities. The COVID-19 pandemic is constantly evolving, and aggressive
efforts are needed to contain the spread. CDC will continue to evaluate and
update our recommendations as the situation evolves.
What is the No Sail Order?
In response to the unprecedented COVID-19 pandemic and the increased risk of
spread of COVID-19 on cruise ships, CDC published the first industry-wide No
Sail Order on March 14 to
prevent, among other things, new passengers from boarding cruise ships. CDC
extended its No Sail Order, effective April 15, 2020, to continue to suspend
all cruise ship operations in waters subject to US jurisdiction. Among other
things, cruise lines are required to develop comprehensive plans to prevent,
detect, respond to, and contain COVID-19 on their cruise ships to protect the
health and safety of both passengers and crew.
How long is the No Sail Order in effect?
The extended Order is in effect until one of the following occurs:

The Secretary of Health and Human Services declares that COVID-19 no longer constitutes a public health emergency, or
The CDC Director rescinds or modifies the order based on specific public health or other considerations, or
100 days have passed from April 15, the date the extended order was published in the Federal Register and went into effect. 100 days from April 15 is July 24.

Why did CDC extend the No Sail Order?
The No Sail Order was extended to protect the public, cruise ship passengers,
cruise ship crews, and other industry workers. By restricting cruise ship
passenger operations, the Order helps achieve several public health goals:

Prevents further spread of COVID-19 into and within the United States
Preserves critical federal, state, and local resources that are needed to respond to COVID-19
Preserves critical healthcare, emergency, and port resources

What cruise ships does the No Sail Order cover?
The No Sail Order applies to all cruise ships, which it defines as commercial
passenger ships with the capacity to carry more than 250 people and where an
overnight stay onboard by passengers or crew is anticipated. The Order applies
to all cruise ships operating, or seeking to operate, in waters subject to US
jurisdiction, including those that have previously voluntarily suspended
operations. It does not apply to cargo ships.
What does the No Sail Order mean for my upcoming trip?
Passengers who plan to travel by cruise ship should contact their cruise line
companies directly for further information.
On March 17, 2020, CDC issued a Level 3 travel health
notice
with a clear recommendation to avoid all cruise travel due to ongoing spread
of COVID-19 and the increased risk of person-to-person spread of infectious
diseases on cruise ships. The No Sail Order suspends all cruise ship
operations in waters subject to US jurisdiction.
What is CDC doing to help cruise ships with crew still on board?
We are currently in a phase of the pandemic where it is necessary to implement
strict measures to control the spread of COVID-19. Just as the American public
has a role to play in practicing social distancing, cruise lines have a role
to play in properly caring for their crew, including making sure they can
practice social distancing, isolating them if they are sick, and quarantining
them if they have been exposed to COVID-19.
CDC is committed to the safety and well-being of crew members while onboard
and as they disembark. CDC is allowing crew members to disembark from cruise
ships in U.S. waters and return home if cruise lines submit a signed
attestation stating that they
have complied with requirements to safely disembark their crew members. Crew
members who remain onboard and want to disembark should contact their cruise
ship or cruise line about meeting CDC requirements for safe disembarkation and
transport. A list of disembarkations that CDC has approved is available
here.
Crew members on ships in or intending to be in US waters who have questions
about the process for disembarkation or who have concerns about what their
ship is doing to prevent COVID-19 onboard can share their questions or
concerns with CDC by sending an email to
eocevent431@cdc.gov.
Cruise ships have medical facilities on board that can provide medical care to
sick crew members as needed. As part of their cruise ship plans, cruise lines
should make sure they have enough medical staff, equipment, supplies, and
other resources to provide care for sick people on board. They also need a
plan to transfer sick crew members to a hospital on land if they need medical
care that the ship’s medical facility can’t provide.
CDC and federal partners are monitoring ships with crew only, and we are
working with the cruise companies and local and state health departments to
ensure that seriously ill crew members can get medical assistance on land if
the ship can’t provide it. CDC remains committed to humanitarian medical
evacuation for people in need of lifesaving support. Emergency medical
evacuations do not require CDC approval.
What is CDC doing to help cruise ships with passengers still on board?
A small number of passengers are still aboard cruise ships in and around US
waters. These passengers are awaiting repatriation to their home countries.
CDC is working with partners as part of the Unified Command, including Coast
Guard, Customs and Border Protection, port authorities, local and state health
departments, and Department of State, along with cruise lines, to help
remaining cruise ship passengers get home as quickly and safely as possible.
These are cruise ships that had international voyages with U.S. ports, and
therefore are under CDC jurisdiction. International voyages without U.S. ports
of call are not under CDC jurisdiction and not included.
International cruise voyages with U.S. domestic ports of call have been
suspended since March 14, 2020, under CDC’s No Sail
Order. Therefore, this chart is available
for historical purposes but is no longer being updated.
Cruise Ships Affected by COVID-19 Ship name | Voyage Start Date | Voyage End
Date
---|---|---
Carnival Freedom | 8-Mar | 15-Mar
Carnival Imagination | 5-Mar | 8-Mar
Carnival Valor | 29-Feb | 5-Mar
Carnival Valor | 5-Mar | 9-Mar
Carnival Valor | 9-Mar | 14-Mar
Carnival Vista | 15-Feb | 22-Feb
Carnival Vista | 29-Feb | 7-Mar
Celebrity Eclipse | 2-Mar | 30-Mar
Celebrity Infinity | 5-Mar | 9-Mar
Celebrity Reflection | 13-Mar | 17-Mar
Celebrity Summit | 29-Feb | 7-Mar
Coral Princess | 5-Mar | 4-Apr
Crown Princess | 6-Mar | 16-Mar
Disney Wonder | 28-Feb | 2-Mar
Disney Wonder | 6-Mar | 20-Mar
Grand Princess | 11-Feb | 21-Feb
Grand Princess | 21-Feb | 7-Mar
Holland America Zaandam | 7-Mar | 2-Apr
MSC Armonia | 2-Mar | 9-Mar
MSC Meraviglia | 1-Mar | 8-Mar
Norwegian Bliss | 1-Mar | 8-Mar
Norwegian Bliss | 8-Mar | 15-Mar
Norwegian Breakaway | 29-Feb | 7-Mar
Norwegian Breakaway | 7-Mar | 14-Mar
Norwegian Encore | 8-Mar | 15-Mar
Oceania Riviera | 26-Feb | 11-Mar
RCCL Explorer of Seas | 8-Mar | 15-Mar
RCCL Liberty of the Seas | 15-Mar | 29-Mar
RCCL Majesty of the Seas | 29-Feb | 7-Mar
RCCL Rhapsody of the Seas | 7-Mar | 14-Mar
RCCL Oasis of the Seas | 8-Mar | 15-Mar
RCCL Symphony of the Seas* | 7-Mar | 14-Mar  
*CDC was notified about COVID-19-positive travelers who had symptoms while on
board these ships.
For all other ships, CDC was notified about travelers who had symptoms and
tested positive for COVID-19 within 14 days after disembarking. Since these
travelers’ symptoms began after the voyage, the traveler might have contracted
COVID-19 during the voyage; however, other sources of transmission after the
voyage cannot be ruled out.

Reviewer feedback on this answer:
There is nothing in particular about shipyards, but it is related to the shipping industry.  There is a lot of information here.
This is an exhaustive list of what the CDC is doing for ships at sea both commercially and publicly.
This answer give firm examples on how to keep people safe and provide multiple examples on how

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