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Class X Prospectus | INCOME PLUS PORTFOLIO

INCOME PLUS PORTFOLIO

June 30, 2021

Supplement

SUPPLEMENT DATED JUNE 30, 2021 TO THE PROSPECTUS OF
MORGAN STANLEY VARIABLE INVESTMENT SERIES
INCOME PLUS PORTFOLIO (the "Fund")
CLASS X
Dated April 30, 2021

At a meeting held on June 15-17, 2021, the Board of Trustees of Morgan Stanley Variable Investment Series approved a reduction in the expense limitation for Class X shares of the Fund effective July 1, 2021.

Accordingly, effective July 1, 2021, the sections of the Prospectus entitled "Fund Summary—Fees and Expenses of the Fund—Annual Fund Operating Expenses" and "Fund Summary—Fees and Expenses of the Fund—Example" are hereby deleted and replaced with the following, which reflects a reduced expense limitation:

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	Class X Prospectus INCOME PLUS PORTFOLIO X
Advisory Fee	0.42%
Distribution (12b-1) Fee	none
Other Expenses	0.49%
Total Annual Fund Operating Expenses	0.91%	[1]
Fee Waiver and/or Expense Reimbursement	0.16%	[1]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	0.75%	[1]

Example

The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the Fund, your investment has a 5% return each year, and the Fund's operating expenses remain the same (except that the example incorporates the fee waiver and/or expense reimbursement arrangement for only the first year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Class X Prospectus | INCOME PLUS PORTFOLIO | X | USD ($)	77	274	488	1,105

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.

[1] The Fund's "Adviser" and "Administrator," Morgan Stanley Investment Management Inc., has agreed to reduce its advisory fee, its administration fee, and/or reimburse the Fund so that Total Annual Fund Operating Expenses, excluding acquired fund fees and expenses (as applicable), certain investment related expenses, taxes, interest and other extraordinary expenses (including litigation), will not exceed 0.75%. The fee waivers and/or expense reimbursements will continue for at least one year from the date of this Prospectus or until such time as the Trust's Board of Trustees acts to discontinue all or a portion of such waivers and/or reimbursements when it deems such action is appropriate. Fee Waiver and/or Expense Reimbursement and Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement have been restated to reflect the current expense limitation arrangement.